Missing thumbnails

If you have a specific technical inquiry, construct your post with the following:


  • Good day we are experiencing a situation where folder thumbnails are disappearing from our virtual machine, is there a specific reason this happened?

Technical details

  • Kolibri version: 0.15.12
  • Operating system: Linux Ubuntu
  • Browser: chrome

Is there a specific event that seems to precipitate them disappearing? In what way have they disappeared? Are they showing up as broken images, or are the folders just showing a simple folder icon and nothing more?

Kind Regards,

Hi @richard they show just a simple folder icon and we have also picked up that some of the channels have disappeared from the platform completely

The only thing I can think of is that we have experienced some issues using SQLite in some virtual machines, because of compatibility issues between the virtualized file system and SQLite. What operating system are you running in the virtual machine? Are you using a SQLite backend? Have you noticed any logging about errors reading from the database in the logs that might have happened when trying to page the WAL file into the main database?

@richard I’m running the virtual machine on a linux server and using Postgres database, I have not noticed any loggings for errors reading from the database.

OK - that’s definitely not a SQLite issue then!

When the thumbnails or channels disappear, is it for all users, or just for some users? What are you using for your caching backend?

It is for all the users @richard

When you say that the channels have disappeared entirely, is that only when looking at it through the Learn interface, or have they also vanished when looking at the imported channels/importing more work flows in the Device app?

@richard it is when we look at it from the imported channels interface as well as in the learner interface, and the weird thing is even when they disappear they somehow seem to still occupy disk space on the virtual machine because every time we reload them we load the same amount of disk space. we are hosting the platform on a 160GB virtual machine, according to our Kolibri studio channel sizes our current content is about 101.57GB and yet the learner interface platform says we only have 1GB of storage left on the virtual machine. Please help


  1. What installation method did you use for Kolibri? For example, installation via pip, the Debian package, a PEX, or perhaps with the kolibri-server package
  2. Do you see any errors in the browser’s developer tools console when you open the page where the thumbnails are missing?
  3. Could you provide a screenshot of the browser having the kolibri page and the developer tools console open?

We used the debian package installation, i have attached sreenshots of the browser developer console

Hi @William.

Thank you for your response and for sharing the screenshots as requested. However, we are specifically interested in the content of the Console tab rather than that of the Elements tab(Please see screen shot below).

Once you navigate to the pages containing the missing thumbnails, switch to the Console tab. Afterward, it would be beneficial to refresh the page, allowing you to capture all console logs for that particular page as it loads. If existent, these logs could help provide some clues on why the thumbnails are missing.

Thank you for your cooperation,

@akolson the console comes back blank, see the attached image

@William Thank you for providing the console screenshot as requested. Unfortunately it doesn’t reveal any insights(as you point out) into the issue. At this point, it would require additional information to pinpoint the issue. We will continue to investigate on our end and ask any follow-up questions; hopefully something comes up in the process.

In the meantime, if you encounter any new information or there are specific steps you would like us to take in order to replicate the issue, please feel free to update this thread as this will be helpful in its resolution.

Thanks for your patience and understanding,

@William To clarify, the ‘English’ folder in your second screenshot is missing thumbnails for the sub-folders ‘Language’, ‘Writing’, etc.? Could you also DM me the channel ID those are from?

@blaine Yes the thumbnails are missing from subfolders mostly but there’s so much missing it’s almost in every channel we have.

@William I was able to find those resources on Kolibri Studio. I do not see that those folders have thumbnails. I also imported the channel and verified that there are no thumbnails for those resources. Did you upload thumbnails to those folders on Kolibri Studio? That is necessary for thumbnails to display