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Sorry to hear you’re facing problems 
help.nextcloud.com is for home/non-enterprise users. If you’re running a business, paid support can be accessed via portal.nextcloud.com where we can ensure your business keeps running smoothly.
In order to help you as quickly as possible, before clicking Create Topic please provide as much of the below as you can. Feel free to use a pastebin service for logs, otherwise either indent short log examples with four spaces:
example
Or for longer, use three backticks above and below the code snippet:
longer
example
here
Some or all of the below information will be requested if it isn’t supplied; for fastest response please provide as much as you can 
Nextcloud version (eg, 20.0.5): 27.0.1
Operating system and version (eg, Ubuntu 20.04): debian 12
Apache or nginx version (eg, Apache 2.4.25): nginx latest
PHP version (eg, 7.4): 8.1
The issue you are facing:
some files mostly excel files show this error: @page { margin: 2cm }
- Cannot decrypt this file, probably this is a shared file. Please ask the file owner to reshare the file with you. after upgrading to this version. this is in office and when trying to download.
Is this the first time you’ve seen this error? (Y):
Steps to replicate it:
- upgrade your nextcloud installation from nc 25 to nc 26 and instantly upgrade to nc 27
The output of your Nextcloud log in Admin > Logging:
{"reqId":"yp1Vo3iurMSVYADqsNbo","level":3,"time":"2023-07-25T13:06:03+00:00","remoteAddr":"192.168.5.14","user":"pandacraft","app":"webdav","method":"GET","url":"/remote.php/dav/files/pandacraft/PixelHosting/Ipmanager.xlsx","message":"Cannot decrypt this file, probably this is a shared file. Please ask the file owner to reshare the file with you.","userAgent":"Mozilla/5.0 (Windows) mirall/3.9.0stable-Win64 (build 20230613) (Nextcloud, windows-10.0.22000 ClientArchitecture: x86_64 OsArchitecture: x86_64)","version":"27.0.1.2","exception":{"Exception":"OC\\Encryption\\Exceptions\\DecryptionFailedException","Message":"Cannot decrypt this file, probably this is a shared file. Please ask the file owner to reshare the file with you.","Code":0,"Trace":[{"file":"/var/www/nextcloud/lib/private/Files/Stream/Encryption.php","line":517,"function":"decrypt","class":"OCA\\Encryption\\Crypto\\Encryption","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"/var/www/nextcloud/lib/private/Files/Stream/Encryption.php","line":316,"function":"readCache","class":"OC\\Files\\Stream\\Encryption","type":"->"},{"function":"stream_read","class":"OC\\Files\\Stream\\Encryption","type":"->"},{"file":"/var/www/nextcloud/3rdparty/icewind/streams/src/Wrapper.php","line":55,"function":"fread"},{"file":"/var/www/nextcloud/3rdparty/icewind/streams/src/CallbackWrapper.php","line":96,"function":"stream_read","class":"Icewind\\Streams\\Wrapper","type":"->"},{"function":"stream_read","class":"Icewind\\Streams\\CallbackWrapper","type":"->"},{"file":"/var/www/nextcloud/3rdparty/sabre/http/lib/Sapi.php","line":110,"function":"stream_copy_to_stream"},{"file":"/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php","line":490,"function":"sendResponse","class":"Sabre\\HTTP\\Sapi","type":"::"},{"file":"/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php","line":253,"function":"invokeMethod","class":"Sabre\\DAV\\Server","type":"->"},{"file":"/var/www/nextcloud/3rdparty/sabre/dav/lib/DAV/Server.php","line":321,"function":"start","class":"Sabre\\DAV\\Server","type":"->"},{"file":"/var/www/nextcloud/apps/dav/lib/Server.php","line":364,"function":"exec","class":"Sabre\\DAV\\Server","type":"->"},{"file":"/var/www/nextcloud/apps/dav/appinfo/v2/remote.php","line":35,"function":"exec","class":"OCA\\DAV\\Server","type":"->"},{"file":"/var/www/nextcloud/remote.php","line":172,"args":["/var/www/nextcloud/apps/dav/appinfo/v2/remote.php"],"function":"require_once"}],"File":"/var/www/nextcloud/apps/encryption/lib/Crypto/Encryption.php","Line":398,"Hint":"Kan dit bestand niet ontcijferen, waarschijnlijk is het een gedeeld bestand, Vraag de eigenaar om het bestand opnieuw met je te delen.","message":"Cannot decrypt this file, probably this is a shared file. Please ask the file owner to reshare the file with you.","exception":[],"CustomMessage":"Cannot decrypt this file, probably this is a shared file. Please ask the file owner to reshare the file with you."},"id":"64bfc8e7b21ff"}
The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
<?php
$CONFIG = array (
'instanceid' => 'REMOVED',
'passwordsalt' => 'REMOVED',
'secret' => 'REMOVED',
'trusted_domains' =>
array (
0 => 'REMOVED',
1 => '192.168.5.36',
2 => 'REMOVED',
3 => '192.168.5.173',
),
'allow_local_remote_servers' => true,
'datadirectory' => '/opt/nextcloud-data',
'dbtype' => 'mysql',
'version' => '27.0.1.2',
'overwrite.cli.url' => 'REMOVED',
'dbname' => 'nextcloud_db',
'dbhost' => 'localhost',
'dbport' => '',
'dbtableprefix' => 'oc_',
'mysql.utf8mb4' => true,
'dbuser' => 'REMOVED',
'dbpassword' => 'REMOVED',
'installed' => true,
'mail_smtpmode' => 'smtp',
'mail_smtpsecure' => 'ssl',
'mail_sendmailmode' => 'smtp',
'mail_from_address' => 'cloud',
'mail_domain' => 'REMOVED',
'mail_smtpauthtype' => 'LOGIN',
'mail_smtpauth' => 1,
'mail_smtphost' => 'REMOVED',
'mail_smtpport' => '465',
'mail_smtpname' => 'REMOVED',
'mail_smtppassword' => 'REMOVED',
'app_install_overwrite' =>
array (
0 => 'radio',
1 => 'impersonate',
2 => 'extract',
3 => 'quicknotes',
4 => 'ransomware_protection',
5 => 'cms_pico',
6 => 'files_downloadactivity',
),
'maintenance' => false,
'preview_max_memory' => 1024,
'preview_max_x' => 512,
'preview_max_y' => 512,
'preview_max_scale_factor' => 1,
'default_phone_region' => 'NL',
'overwriteprotocol' => 'https',
'overwritehost' => 'REMOVED',
'memcache.local' => '\\OC\\Memcache\\Redis',
'memcache.locking' => '\\OC\\Memcache\\Redis',
'memcache.distributed' => '\\OC\\Memcache\\Redis',
'redis' =>
array (
'host' => '/var/run/redis/redis-server.sock',
'port' => 0,
'dbindex' => 0,
'timeout' => 1.5,
),
'theme' => '',
'loglevel' => 2,
'twofactor_enforced' => 'true',
'twofactor_enforced_groups' =>
array (
0 => 'PixelHosting',
1 => 'admin',
),
'twofactor_enforced_excluded_groups' =>
array (
),
'enabledPreviewProviders' =>
array (
1 => 'OC\\Preview\\Movie',
2 => 'OC\\Preview\\PNG',
3 => 'OC\\Preview\\JPEG',
4 => 'OC\\Preview\\GIF',
5 => 'OC\\Preview\\BMP',
6 => 'OC\\Preview\\XBitmap',
7 => 'OC\\Preview\\MP3',
8 => 'OC\\Preview\\MP4',
9 => 'OC\\Preview\\TXT',
10 => 'OC\\Preview\\MarkDown',
11 => 'OC\\Preview\\PDF',
12 => 'OC\\Preview\\MKV',
13 => 'OC\\Preview\\MSOffice2003',
14 => 'OC\\Preview\\MSOffice2007',
15 => 'OC\\Preview\\MSOfficeDoc',
16 => 'OC\\Preview\\OpenDocument',
17 => 'OC\\Preview\\StarOffice',
),
'updater.release.channel' => 'stable',
'trusted_proxies' =>
array (
0 => '127.0.0.1',
1 => '::1',
2 => '192.168.5.173',
),
);
The output of your Apache/nginx/system log in /var/log/____:
no logs
no logs
Output errors in nextcloud.log in /var/www/ or as admin user in top right menu, filtering for errors. Use a pastebin service if necessary.
{"reqId":"KF7Ybfm6Rb6FJtSYvCBI","level":3,"time":"2023-07-25T13:06:53+00:00","remoteAddr":"192.168.5.14","user":"pandacraft","app":"no app in context","method":"GET","url":"/remote.php/dav/files/pandacraft/PixelHosting/Ipmanager.xlsx","message":"Cannot decrypt this file, probably this is a shared file. Please ask the file owner to reshare the file with you.","userAgent":"Mozilla/5.0 (Windows) mirall/3.9.0stable-Win64 (build 20230613) (Nextcloud, windows-10.0.22000 ClientArchitecture: x86_64 OsArchitecture: x86_64)","version":"27.0.1.2","data":[],"id":"64bfca03d3d0f"}