13.0.5.2 to 13.0.6 Update Failes at Create Backup

Nextcloud version (eg, 13.0.5.2): 13.0.5.2
Operating system and version (eg, Ubuntu 17.04): https://bernstein.metanet.ch:8443/smb/web/php-info/id/554
Apache or nginx version (eg, Apache 2.4.25): https://bernstein.metanet.ch:8443/smb/web/php-info/id/554
PHP version (eg, 7.1): https://bernstein.metanet.ch:8443/smb/web/php-info/id/554

The issue you are facing: Trying to update from 13.0.5.2 to 13.0.6 (production channel)

Is this the first time you’ve seen this error? (Y/N): Y

Steps to replicate it:

  1. Log in to admin panel of nextcloud
  2. Settings -> General -> start Update
  3. On updater page click start update

The output of your Nextcloud log in Admin > Logging:

{"reqId":"W3RAJTlgg9l6rPh9c7wYWQAAAAE","level":3,"time":"2018-08-15T15:00:55+00:00","remoteAddr":"0.0.0.0","user":"admin","app":"PHP","method":"POST","url":"\/index.php\/settings\/ajax\/enableapp.php","message":"include(\/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/3rdparty\/pear\/archive_tar\/Archive\/Tar.php): failed to open stream: Permission denied at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/composer\/composer\/ClassLoader.php#444","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko\/20100101 Firefox\/61.0","version":"13.0.5.2"}
{"reqId":"W3RAJTlgg9l6rPh9c7wYWQAAAAE","level":3,"time":"2018-08-15T15:00:55+00:00","remoteAddr":"0.0.0.0","user":"admin","app":"PHP","method":"POST","url":"\/index.php\/settings\/ajax\/enableapp.php","message":"include(\/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/3rdparty\/pear\/archive_tar\/Archive\/Tar.php): failed to open stream: Permission denied at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/composer\/composer\/ClassLoader.php#444","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko\/20100101 Firefox\/61.0","version":"13.0.5.2"}
{"reqId":"W3RAJTlgg9l6rPh9c7wYWQAAAAE","level":3,"time":"2018-08-15T15:00:55+00:00","remoteAddr":"0.0.0.0","user":"admin","app":"PHP","method":"POST","url":"\/index.php\/settings\/ajax\/enableapp.php","message":"include(): Failed opening '\/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/3rdparty\/composer\/..\/pear\/archive_tar\/Archive\/Tar.php' for inclusion (include_path='\/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/3rdparty\/pear\/console_getopt:\/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/3rdparty\/pear\/pear_exception:\/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/3rdparty\/pear\/pear-core-minimal\/src:\/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/3rdparty\/pear\/archive_tar:\/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/apps') at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/composer\/composer\/ClassLoader.php#444","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko\/20100101 Firefox\/61.0","version":"13.0.5.2"}
{"reqId":"W3RAJTlgg9l6rPh9c7wYWQAAAAE","level":3,"time":"2018-08-15T15:00:55+00:00","remoteAddr":"0.0.0.0","user":"admin","app":"index","method":"POST","url":"\/index.php\/settings\/ajax\/enableapp.php","message":"Exception: {\"Exception\":\"Error\",\"Message\":\"Class 'Archive_Tar' not found\",\"Code\":0,\"Trace\":\"#0 \\\/home\\\/httpd\\\/vhosts\\\/domain.eu\\\/cloud.domain.eu\\\/lib\\\/private\\\/Installer.php(284): OC\\\\Archive\\\\TAR->__construct('\\\/tmp\\\/oc_tmp_10C...')\\n#1 \\\/home\\\/httpd\\\/vhosts\\\/domain.eu\\\/cloud.domain.eu\\\/lib\\\/private\\\/legacy\\\/app.php(384): OC\\\\Installer->downloadApp('drawio')\\n#2 \\\/home\\\/httpd\\\/vhosts\\\/domain.eu\\\/cloud.domain.eu\\\/settings\\\/ajax\\\/enableapp.php(45): OC_App->enable('drawio', NULL)\\n#3 \\\/home\\\/httpd\\\/vhosts\\\/domain.eu\\\/cloud.domain.eu\\\/lib\\\/private\\\/Route\\\/Route.php(155): require_once('\\\/home\\\/httpd\\\/vho...')\\n#4 [internal function]: OC\\\\Route\\\\Route->OC\\\\Route\\\\{closure}(*** sensitive parameters replaced ***)\\n#5 \\\/home\\\/httpd\\\/vhosts\\\/domain.eu\\\/cloud.domain.eu\\\/lib\\\/private\\\/Route\\\/Router.php(297): call_user_func(Object(Closure), Array)\\n#6 \\\/home\\\/httpd\\\/vhosts\\\/domain.eu\\\/cloud.domain.eu\\\/lib\\\/base.php(999): OC\\\\Route\\\\Router->match('\\\/settings\\\/ajax\\\/...')\\n#7 \\\/home\\\/httpd\\\/vhosts\\\/domain.eu\\\/cloud.domain.eu\\\/index.php(42): OC::handleRequest()\\n#8 {main}\",\"File\":\"\\\/home\\\/httpd\\\/vhosts\\\/domain.eu\\\/cloud.domain.eu\\\/lib\\\/private\\\/Archive\\\/TAR.php\",\"Line\":57}","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko\/20100101 Firefox\/61.0","version":"13.0.5.2"}
{"reqId":"W3RIGP@7sgb@t041wsdBoAAAAAM","level":3,"time":"2018-08-15T15:34:49+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko\/20100101 Firefox\/61.0","version":"13.0.5.2"}
{"reqId":"W3RIGP@7sgb@t041wsdBoAAAAAM","level":3,"time":"2018-08-15T15:34:49+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko\/20100101 Firefox\/61.0","version":"13.0.5.2"}
{"reqId":"W3UOkLtSDx767YxPQy7ywwAAAAM","level":3,"time":"2018-08-16T05:41:36+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W3UOkLtSDx767YxPQy7ywwAAAAM","level":3,"time":"2018-08-16T05:41:36+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W3Zg7w7LmIm3vfFONq7hjQAAAAo","level":3,"time":"2018-08-17T05:45:19+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W3Zg7w7LmIm3vfFONq7hjQAAAAo","level":3,"time":"2018-08-17T05:45:19+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W3bI2vNW-bGhmu7XAoEFlgAAAAc","level":3,"time":"2018-08-17T13:08:42+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko\/20100101 Firefox\/61.0","version":"13.0.5.2"}
{"reqId":"W3bI2vNW-bGhmu7XAoEFlgAAAAc","level":3,"time":"2018-08-17T13:08:42+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko\/20100101 Firefox\/61.0","version":"13.0.5.2"}
{"reqId":"W3pTpvc11vJI4HYHVs@IugAAABI","level":3,"time":"2018-08-20T05:37:43+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W3pTpvc11vJI4HYHVs@IugAAABI","level":3,"time":"2018-08-20T05:37:43+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W3ukzu1GGRpCOYM0nuRD8AAAAAc","level":3,"time":"2018-08-21T05:36:14+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W3ukzu1GGRpCOYM0nuRD8AAAAAc","level":3,"time":"2018-08-21T05:36:14+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W3z17oe5ycwnhxEBPLFSUgAAAAA","level":3,"time":"2018-08-22T05:34:38+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W3z17oe5ycwnhxEBPLFSUgAAAAA","level":3,"time":"2018-08-22T05:34:38+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W35I-6jGI-7wWiPmfJqpzwAAADE","level":3,"time":"2018-08-23T05:41:19+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W35I-6jGI-7wWiPmfJqpzwAAADE","level":3,"time":"2018-08-23T05:41:19+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W36cU-XQMKjYBe9a5SRsugAAAAk","level":3,"time":"2018-08-23T11:36:52+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W36cU-XQMKjYBe9a5SRsugAAAAk","level":3,"time":"2018-08-23T11:36:52+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W3@aRvV73u1TTwbzdzQBQQAAAAE","level":3,"time":"2018-08-24T05:40:22+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W3@aRvV73u1TTwbzdzQBQQAAAAE","level":3,"time":"2018-08-24T05:40:22+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W4Aanip0AxYuQi4nrD4wnwAAAAg","level":3,"time":"2018-08-24T14:47:58+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko\/20100101 Firefox\/61.0","version":"13.0.5.2"}
{"reqId":"W4Aanip0AxYuQi4nrD4wnwAAAAg","level":3,"time":"2018-08-24T14:47:58+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko\/20100101 Firefox\/61.0","version":"13.0.5.2"}
{"reqId":"W4JgKVyTfsoDu8KUnpvslgAAAAA","level":3,"time":"2018-08-26T08:09:14+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko\/20100101 Firefox\/61.0","version":"13.0.5.2"}
{"reqId":"W4JgKVyTfsoDu8KUnpvslgAAAAA","level":3,"time":"2018-08-26T08:09:14+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko\/20100101 Firefox\/61.0","version":"13.0.5.2"}
{"reqId":"W4ONzHRF3CVQ2qb84T68ggAAAA8","level":3,"time":"2018-08-27T05:36:12+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W4ONzHRF3CVQ2qb84T68ggAAAA8","level":3,"time":"2018-08-27T05:36:12+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W4Td@zRGXmyn0rqquMwT-QAAAAw","level":3,"time":"2018-08-28T05:30:35+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W4Td@zRGXmyn0rqquMwT-QAAAAw","level":3,"time":"2018-08-28T05:30:35+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W4Y@CW@0yga9WWf-RhPlRQAAAAA","level":3,"time":"2018-08-29T06:32:42+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W4Y@CW@0yga9WWf-RhPlRQAAAAA","level":3,"time":"2018-08-29T06:32:42+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W4aVM8PmQZMasWZM8706iAAAABA","level":3,"time":"2018-08-29T12:44:35+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W4aVM8PmQZMasWZM8706iAAAABA","level":3,"time":"2018-08-29T12:44:35+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W4bJyJQHPNTdyWT6AYRLagAAAAI","level":3,"time":"2018-08-29T16:28:56+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit\/537.36 (KHTML, like Gecko) Chrome\/64.0.3282.140 Safari\/537.36 Edge\/17.17134","version":"13.0.5.2"}
{"reqId":"W4bJyJQHPNTdyWT6AYRLagAAAAI","level":3,"time":"2018-08-29T16:28:56+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit\/537.36 (KHTML, like Gecko) Chrome\/64.0.3282.140 Safari\/537.36 Edge\/17.17134","version":"13.0.5.2"}
{"reqId":"W4eHt6Fy2vOXWyqd-FAZEQAAAAw","level":3,"time":"2018-08-30T05:59:19+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W4eHt6Fy2vOXWyqd-FAZEQAAAAw","level":3,"time":"2018-08-30T05:59:19+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W4jS50Sox-sEy3SSdhUMFwAAABM","level":3,"time":"2018-08-31T05:32:23+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W4jS50Sox-sEy3SSdhUMFwAAABM","level":3,"time":"2018-08-31T05:32:23+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W4ly7NuLjzgR8nPYzQpnjQAAAAE","level":3,"time":"2018-08-31T16:55:08+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko\/20100101 Firefox\/61.0","version":"13.0.5.2"}
{"reqId":"W4ly7NuLjzgR8nPYzQpnjQAAAAE","level":3,"time":"2018-08-31T16:55:08+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko\/20100101 Firefox\/61.0","version":"13.0.5.2"}
{"reqId":"W4l8u9Frqa88muEEn6Hc3QAAAAA","level":3,"time":"2018-08-31T17:36:59+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko\/20100101 Firefox\/61.0","version":"13.0.5.2"}
{"reqId":"W4l8u9Frqa88muEEn6Hc3QAAAAA","level":3,"time":"2018-08-31T17:36:59+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko\/20100101 Firefox\/61.0","version":"13.0.5.2"}
{"reqId":"W4zHcKCXsEtMyoHpKxeZbwAAAAM","level":3,"time":"2018-09-03T05:32:32+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W4zHcKCXsEtMyoHpKxeZbwAAAAM","level":3,"time":"2018-09-03T05:32:32+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W44aYBfbhqP8l6X@uW1X2QAAAAI","level":3,"time":"2018-09-04T05:38:41+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W44aYBfbhqP8l6X@uW1X2QAAAAI","level":3,"time":"2018-09-04T05:38:41+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W49qAuLWknIIrkR8xQyZOAAAAAg","level":3,"time":"2018-09-05T05:30:43+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W49qAuLWknIIrkR8xQyZOAAAAAg","level":3,"time":"2018-09-05T05:30:43+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W5DBXxIn--WKvv@lbUHYGAAAAAo","level":3,"time":"2018-09-06T05:55:44+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W5DBXxIn--WKvv@lbUHYGAAAAAo","level":3,"time":"2018-09-06T05:55:44+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko\/20100101 Firefox\/52.0","version":"13.0.5.2"}
{"reqId":"W5INL7WB4ZkBrN-v@35EcAAAABI","level":3,"time":"2018-09-07T05:31:27+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"vsprintf(): Too few arguments at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10NString.php#79","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko\/20100101 Firefox\/60.0","version":"13.0.5.2"}
{"reqId":"W5INL7WB4ZkBrN-v@35EcAAAABI","level":3,"time":"2018-09-07T05:31:27+00:00","remoteAddr":"0.0.0.0","user":"daniel","app":"PHP","method":"GET","url":"\/index.php\/apps\/passman\/api\/v2\/language?lang=en","message":"Method OC\\L10N\\L10NString::__toString() must return a string value at \/home\/httpd\/vhosts\/domain.eu\/cloud.domain.eu\/lib\/private\/L10N\/L10N.php#88","userAgent":"Mozilla\/5.0 (Windows NT 6.1; WOW64; rv:60.0) Gecko\/20100101 Firefox\/60.0","version":"13.0.5.2"}

The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):

<?php
$CONFIG = array (
  'instanceid' => 'xxxxx',
  'passwordsalt' => 'xxxxxx',
  'secret' => 'xxxxxxxx',
  'trusted_domains' => 
  array (
    0 => 'cloud.domain.eu',
  ),
  'datadirectory' => '/home/httpd/vhosts/domain.eu/cloud.domain.eu/data',
  'overwrite.cli.url' => 'https://cloud.domain.eu',
  'dbtype' => 'mysql',
  'version' => '13.0.5.2',
  'dbname' => 'danielh_cloud',
  'dbhost' => 'localhost',
  'dbport' => '',
  'dbtableprefix' => 'oc_',
  'mysql.utf8mb4' => true,
  'dbuser' => 'danielh_cloud',
  'dbpassword' => 'xxxx',
  'installed' => true,
  'maintenance' => false,
  'theme' => '',
  'loglevel' => 1,
  'mail_smtpmode' => 'php',
  'mail_smtpauthtype' => 'LOGIN',
  'updater.release.channel' => 'production',
  'auth.bruteforce.protection.enabled' => true,
  'activity_expire_days' => 365,
  'updater.secret' => 'xxxxx',
);

The output of your Apache/nginx/system log in /var/log/____:

no file found under /var/log

Get the same error and do manually update and get integrity issues. Will write an extra post.