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The Basics
- Nextcloud Server version (e.g., 29.x.x):
- Nextcloud AIO using 32.0.1
- Operating system and version (e.g., Ubuntu 24.04):
- host is Ubuntu 24.04
- Reverse proxy and version _(e.g. nginx 1.27.2)
Caddy- separate server
- PHP version (e.g, 8.3):
whatever AIO uses
- Is this the first time you’ve seen this error? (Yes / No):
no
- When did this problem seem to first start?
since installation a week or so ago
- Installation method (e.g. AlO, NCP, Bare Metal/Archive, etc.)
AIO
- Are you using CloudfIare, mod_security, or similar? (Yes / No)
don't know what that is, but I don't think so.
Summary of the issue you are facing:
I am seeing a ton of:
ServerException
Server error: `POST http://nextcloud-aio-apache:23973/cool/convert-to/png` resulted in a `502 Bad Gateway` response
in the logs.
Steps to replicate it (hint: details matter!):
- not sure. But I assume it has to do with generating png files internally for something?
Log entries
Nextcloud
Please provide the log entries from your Nextcloud log that are generated during the time of problem (via the Copy raw option from Administration settings->Logging screen or from your nextcloud.log located in your data directory). Feel free to use a pastebin/gist service if necessary.
{"reqId":"BZLNXO8kyFvWl6gpHh2m","level":3,"time":"2025-11-17T17:13:20+00:00","remoteAddr":"10.1.10.21","user":"40942F33-437D-45D9-81F9-DAF09710F5E9","app":"richdocuments","method":"GET","url":"/core/preview?fileId=22134&x=250&y=250","message":"Failed to convert preview: Server error: `POST http://nextcloud-aio-apache:23973/cool/convert-to/png` resulted in a `502 Bad Gateway` response","userAgent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36","version":"32.0.1.2","exception":{"Exception":"GuzzleHttp\\Exception\\ServerException","Message":"Server error: `POST http://nextcloud-aio-apache:23973/cool/convert-to/png` resulted in a `502 Bad Gateway` response","Code":502,"Trace":[{"file":"/var/www/html/3rdparty/guzzlehttp/guzzle/src/Middleware.php","line":72,"function":"create","class":"GuzzleHttp\\Exception\\RequestException","type":"::","args":["*** sensitive parameters replaced ***"]},{"file":"/var/www/html/3rdparty/guzzlehttp/promises/src/Promise.php","line":209,"function":"GuzzleHttp\\{closure}","class":"GuzzleHttp\\Middleware","type":"::","args":["*** sensitive parameters replaced ***"]},{"file":"/var/www/html/3rdparty/guzzlehttp/promises/src/Promise.php","line":158,"function":"callHandler","class":"GuzzleHttp\\Promise\\Promise","type":"::","args":[1,"*** sensitive parameters replaced ***","*** sensitive parameters replaced ***"]},{"file":"/var/www/html/3rdparty/guzzlehttp/promises/src/TaskQueue.php","line":52,"function":"GuzzleHttp\\Promise\\{closure}","class":"GuzzleHttp\\Promise\\Promise","type":"::","args":["*** sensitive parameters replaced ***"]},{"file":"/var/www/html/3rdparty/guzzlehttp/promises/src/Promise.php","line":251,"function":"run","class":"GuzzleHttp\\Promise\\TaskQueue","type":"->","args":[true]},{"file":"/var/www/html/3rdparty/guzzlehttp/promises/src/Promise.php","line":227,"function":"invokeWaitFn","class":"GuzzleHttp\\Promise\\Promise","type":"->","args":[]},{"file":"/var/www/html/3rdparty/guzzlehttp/promises/src/Promise.php","line":272,"function":"waitIfPending","class":"GuzzleHttp\\Promise\\Promise","type":"->","args":[]},{"file":"/var/www/html/3rdparty/guzzlehttp/promises/src/Promise.php","line":229,"function":"invokeWaitList","class":"GuzzleHttp\\Promise\\Promise","type":"->","args":[]},{"file":"/var/www/html/3rdparty/guzzlehttp/promises/src/Promise.php","line":69,"function":"waitIfPending","class":"GuzzleHttp\\Promise\\Promise","type":"->","args":[]},{"file":"/var/www/html/3rdparty/guzzlehttp/guzzle/src/Client.php","line":189,"function":"wait","class":"GuzzleHttp\\Promise\\Promise","type":"->","args":[]},{"file":"/var/www/html/lib/private/Http/Client/Client.php","line":277,"function":"request","class":"GuzzleHttp\\Client","type":"->","args":["post","*** sensitive parameters replaced ***",{"0":"And 2 more entries, set log level to debug to see all entries","verify":"/var/www/html/resources/config/ca-bundle.crt","timeout":5,"nextcloud":{"allow_local_address":true},"expect":false,"multipart":[{"name":"._Special 2025 Pricing Calculator for Hiperwall.xlsx","filename":"._Special 2025 Pricing Calculator for Hiperwall.xlsx","contents":null}]}]},{"file":"/var/www/html/custom_apps/richdocuments/lib/Service/RemoteService.php","line":94,"function":"post","class":"OC\\Http\\Client\\Client","type":"->","args":["*** sensitive parameters replaced ***"]},{"file":"/var/www/html/custom_apps/richdocuments/lib/Service/RemoteService.php","line":68,"function":"convertTo","class":"OCA\\Richdocuments\\Service\\RemoteService","type":"->","args":["._Special 2025 Pricing Calculator for Hiperwall.xlsx",null,"png"]},{"file":"/var/www/html/custom_apps/richdocuments/lib/Preview/Office.php","line":43,"function":"convertFileTo","class":"OCA\\Richdocuments\\Service\\RemoteService","type":"->","args":[{"__class__":"OC\\Files\\Node\\File"},"png"]},{"file":"/var/www/html/lib/private/Preview/GeneratorHelper.php","line":45,"function":"getThumbnail","class":"OCA\\Richdocuments\\Preview\\Office","type":"->","args":[{"__class__":"OC\\Files\\Node\\File"},2048,2048]},{"file":"/var/www/html/lib/private/Preview/Generator.php","line":342,"function":"getThumbnail","class":"OC\\Preview\\GeneratorHelper","type":"->","args":[{"__class__":"OCA\\Richdocuments\\Preview\\OOXML"},{"__class__":"OC\\Files\\Node\\File"},2048,2048]},{"file":"/var/www/html/lib/private/Preview/Generator.php","line":313,"function":"generateProviderPreview","class":"OC\\Preview\\Generator","type":"->","args":[{"__class__":"OC\\Files\\SimpleFS\\SimpleFolder"},{"__class__":"OC\\Files\\Node\\File"},2048,2048,false,true,"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",""]},{"file":"/var/www/html/lib/private/Preview/Generator.php","line":117,"function":"getMaxPreview","class":"OC\\Preview\\Generator","type":"->","args":[{"__class__":"OC\\Files\\SimpleFS\\SimpleFolder"},"*** sensitive parameters replaced ***",{"__class__":"OC\\Files\\Node\\File"},"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",""]},{"file":"/var/www/html/lib/private/Preview/Generator.php","line":87,"function":"generatePreviews","class":"OC\\Preview\\Generator","type":"->","args":[{"__class__":"OC\\Files\\Node\\File"},[{"width":250,"height":250,"crop":true,"mode":"fill"}],"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",true]},{"file":"/var/www/html/lib/private/PreviewManager.php","line":161,"function":"getPreview","class":"OC\\Preview\\Generator","type":"->","args":[{"__class__":"OC\\Files\\Node\\File"},250,250,true,"fill","*** sensitive parameters replaced ***",true]},{"file":"/var/www/html/core/Controller/PreviewController.php","line":166,"function":"getPreview","class":"OC\\PreviewManager","type":"->","args":[{"__class__":"OC\\Files\\Node\\File"},250,250,true,"fill"]},{"file":"/var/www/html/core/Controller/PreviewController.php","line":128,"function":"fetchPreview","class":"OC\\Core\\Controller\\PreviewController","type":"->","args":[{"__class__":"OC\\Files\\Node\\File"},250,250,false,true,"fill",false]},{"file":"/var/www/html/lib/private/AppFramework/Http/Dispatcher.php","line":204,"function":"getPreviewByFileId","class":"OC\\Core\\Controller\\PreviewController","type":"->","args":[22134,250,250,false,true,"fill",false]},{"file":"/var/www/html/lib/private/AppFramework/Http/Dispatcher.php","line":118,"function":"executeController","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->","args":[{"__class__":"OC\\Core\\Controller\\PreviewController"},"getPreviewByFileId"]},{"file":"/var/www/html/lib/private/AppFramework/App.php","line":153,"function":"dispatch","class":"OC\\AppFramework\\Http\\Dispatcher","type":"->","args":[{"__class__":"OC\\Core\\Controller\\PreviewController"},"getPreviewByFileId"]},{"file":"/var/www/html/lib/private/Route/Router.php","line":321,"function":"main","class":"OC\\AppFramework\\App","type":"::","args":["OC\\Core\\Controller\\PreviewController","getPreviewByFileId",{"__class__":"OC\\AppFramework\\DependencyInjection\\DIContainer"},{"_route":"core.preview.getpreviewbyfileid"}]},{"file":"/var/www/html/lib/base.php","line":1061,"function":"match","class":"OC\\Route\\Router","type":"->","args":["/core/preview"]},{"file":"/var/www/html/index.php","line":25,"function":"handleRequest","class":"OC","type":"::","args":[]}],"File":"/var/www/html/3rdparty/guzzlehttp/guzzle/src/Exception/RequestException.php","Line":111,"message":"Failed to convert preview: Server error: `POST http://nextcloud-aio-apache:23973/cool/convert-to/png` resulted in a `502 Bad Gateway` response","exception":[],"CustomMessage":"Failed to convert preview: Server error: `POST http://nextcloud-aio-apache:23973/cool/convert-to/png` resulted in a `502 Bad Gateway` response"},"id":"691b591c5d930"}
As stated above, getting a tone of errors in the logs that read:
ServerException
Server error: `POST http://nextcloud-aio-apache:23973/cool/convert-to/png` resulted in a `502 Bad Gateway` response
Any ideas on how to fix?