Picture Preview crashed

when i open a picture over the Gallery App i can’t see it.
Here the Log-File:
{“reqId”:“AYj7dDa0R3wpuK/2lxam”,“remoteAddr”:“”,“app”:“gallery”,“message”:“Exception: Preview generation has failed”,“level”:3,“time”:“2017-04-11T13:43:54+00:00”,“method”:“GET”,“url”:"/index.php/apps/gallery/preview/2624?width=2000&height=2000&c=73769a610fbde3b120ddae9492559c85&requesttoken=Kjc8Ilp9CaPwcdAM%2FjxF3%2FgLQLUupfgNgSXyWC9sVoI%3D%3AXVpsZgstW9CpIJFcsU50to8%2BKIFp461r7E%2BrKGM%2BA9o%3D",“user”:“jung_alex”,“version”:“”}

Any idea ?


This would require some more details to understand the situation. For example the following info would be welcome:

  • Operating sytem
  • NextCloud version
  • Hardware memory
  • Free diskspace
  • Picture size ( height x width)

And other details you can provide.

Hi StephanW,

here the Info’s you need:

Operating system: Ubuntu 16.04 LTS
Nextcloud Version: 11.0.2
Memory: 16 GB
Free diskspace: 38 GB
Picture size: 1024x768

In the File-List I see the thumbnail:

OK from that it doesn’t look like a resource issue.

Could you try to set the log level to 0 and provide the log output. Hopefully this will shed some more light on the issue.

Add the following (or update) in config.php:

'loglevel' => 0,



now i disable the “File Access Control” App an all works fine.
What has this to do with the Gallery App oder the Preview ?

Now i changed the Loglevel but the output in the logfile is the same.

This is strange. I checked and I have “File Access Control” enabled and can view pictures from the file view.

Have you defined any filters on the File Access Control, and if so, could you share them with us? Maybe there is something defined which causes it to be blocked.

I would have hoped it would generate some more details in the logs. But guess for this it doesn’t.

In this post you can see my rules of "File Access Control"

It does look like the filter is the problem.

I create the same filter and hit the same problem. I then added the following rule which made it work again, at least for the preview app:

Which contains the internal IP address of my proxy (Apache).

I am not sure if that would cause issues with other situations for which you are using this filter.

1 Like

Hi Stephan,

I added now my IP address of the proxy and all work fine :slight_smile:

Thanks for your Help !!!