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Sorry to hear you’re facing problems 
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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): replace me
Operating system and version (eg, Ubuntu 20.04): replace me
Apache or nginx version (eg, Apache 2.4.25): replace me
PHP version (eg, 7.4): replace me
The issue you are facing:
Is this the first time you’ve seen this error? (Y/N): no
Steps to replicate it:
1. Deleting files, adding files, setting file sharing, etc. will all appear
2. The above operations will take 10-20 seconds
The output of your Nextcloud log in Admin > Logging:
[PHP] 错误: Error: file_put_contents(/volume1/web/nextcloud/data/appdata_oc1pjpwhky0v/preview/c/4/d/c/0/3/5/12611/794-1123-max.png): Failed to open stream: No such file or directory at /volume1/web/nextcloud/lib/private/Files/Storage/Local.php#311 at <<closure>>
0. <<closure>>
OC\Log\ErrorHandler::onError(2, "file_put_conten ... y", "/volume1/web/ne ... p", 311)
1. /volume1/web/nextcloud/lib/private/Files/Storage/Local.php line 311
file_put_contents("/volume1/web/ne ... g", null)
2. /volume1/web/nextcloud/lib/private/Files/Storage/Wrapper/Wrapper.php line 258
OC\Files\Storage\Local->file_put_contents("appdata_oc1pjpw ... g", null)
3. /volume1/web/nextcloud/lib/private/Files/View.php line 1179
OC\Files\Storage\Wrapper\Wrapper->file_put_contents("appdata_oc1pjpw ... g", null)
4. /volume1/web/nextcloud/lib/private/Files/View.php line 705
OC\Files\View->basicOperation("file_put_contents", "/appdata_oc1pjp ... g", ["create","write"], null)
5. /volume1/web/nextcloud/lib/private/Files/Node/Folder.php line 191
OC\Files\View->file_put_contents("/appdata_oc1pjp ... g", null)
6. /volume1/web/nextcloud/lib/private/Files/SimpleFS/NewSimpleFile.php line 121
OC\Files\Node\Folder->newFile("794-1123-max.png", null)
7. /volume1/web/nextcloud/lib/private/Preview/Generator.php line 363
OC\Files\SimpleFS\NewSimpleFile->putContent(null)
8. /volume1/web/nextcloud/lib/private/Preview/Generator.php line 162
OC\Preview\Generator->getMaxPreview(OC\Files\SimpleFS\SimpleFolder {}, OC\Files\SimpleFS\NewSimpleFile {}, "application/vnd ... t", "")
9. /volume1/web/nextcloud/lib/private/Preview/Generator.php line 114
OC\Preview\Generator->generatePreviews(OC\Files\Node\File {}, [[250,250,true,"fill"]], "application/vnd ... t")
10. /volume1/web/nextcloud/lib/private/PreviewManager.php line 185
OC\Preview\Generator->getPreview(OC\Files\Node\File {}, 250, 250, true, "fill", null)
11. /volume1/web/nextcloud/core/Controller/PreviewController.php line 144
OC\PreviewManage
The output of your config.php file in /path/to/nextcloud (make sure you remove any identifiable information!):
<?php
$CONFIG = array (
'instanceid' => 'o******v',
'passwordsalt' => '9*****t',
'secret' => '+M*******V',
'trusted_domains' =>
array (
0 => '****'
),
'datadirectory' => '/volume1/web/nextcloud/data',
'auth.bruteforce.protection.enabled' => false,
'dbtype' => 'mysql',
'version' => '25.0.1.1',
'simpleSignUpLink.shown' => false,
'overwrite.cli.url' => 'http://192.168.1.6:1000',
'dbname' => 'nextcloud',
'dbhost' => '192.168.1.6:3306',
'dbport' => '',
'dbtableprefix' => 'oc_',
'mysql.utf8mb4' => true,
'dbuser' => '***',
'dbpassword' => '****',
'installed' => true,
'memcache.local' => '\OC\Memcache\APCu',
'memcache.locking' => '\OC\Memcache\Redis',
'redis' => [
'host' => '127.0.0.1',
'port' => 6379,
],
'default_phone_region' => 'CN',
'mail_smtpmode' => 'smtp',
'mail_sendmailmode' => 'smtp',
'mail_from_address' => 'tm426',
'mail_domain' => 'foxmail.com',
'mail_smtpsecure' => 'ssl',
'mail_smtphost' => 'smtp.qq.com',
'mail_smtpport' => '465',
'mail_smtpauthtype' => 'LOGIN',
'mail_smtpauth' => 1,
'mail_smtpname' => '****@foxmail.com',
'mail_smtppassword' => '***',
'app_install_overwrite' =>
array (
0 => 'diary',
1 => 'backup',
),
);
The output of your Apache/nginx/system log in /var/log/____:
2022/12/06 07:03:01 [error] 20354#20354: *1 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 192.168.1.6, server: _, request: "GET /cron.php HTTP/1.1", upstream: "http://127.0.0.1:915/cron.php", host: "192.168.1.6:1000"
2022/12/06 08:37:58 [error] 7421#7421: *312 upstream timed out (110: Connection timed out) while reading response header from upstream, client: 113.87.76.172, server: _, request: "GET /index.php/core/preview?fileId=10919&c=28af84cde89938f1b3f05a31d1fad574&x=250&y=250&forceIcon=0&a=0 HTTP/1.1", upstream: "http://127.0.0.1:915/index.php/core/preview?fileId=10919&c=28af84cde89938f1b3f05a31d1fad574&x=250&y=250&forceIcon=0&a=0", host: "ourzhishi.top:1000"
2022/12/06 10:41:58 [warn] 17312#17312: low address bits of 192.168.1.6/24 are meaningless in /etc/nginx/conf.d/dsm.ssdp.conf:2
2022/12/06 10:41:58 [warn] 17312#17312: low address bits of 169.254.2.108/16 are meaningless in /etc/nginx/conf.d/dsm.ssdp.conf:3
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.
PASTE HERE