Missing or improper thumbnails

Firefox (including its other forks like Librewolf) prevents the app from generating thumbnails if the "block canvas fingerprinting" setting in Firefox is enabled (i.e. privacy.resistFingerprinting is set to true in about:config). The app needs the canvas to generate thumbnails, and that Firefox feature blocks access to the canvas. Ideally, Firefox should be prompting for a permission, but some users have reported that sometime it silently blocks access, and turning off that setting works.

Similar issues may arise if you are using an extension that blocks access to the canvas, or some other browser that has similar restrictions.

In all these cases, you need to allow Ente access to the canvas for the thumbnail to be generated properly.

Note that once the thumbnails are missing or have been incorrectly generated, they cannot be viewed on any of the other clients (the thumbnails are only generated once, during upload, so viewing it in a different place does not change the already generated thumbnail).

There is currently no functionality to regenerate thumbnails in the above cases. You will need to upload the affected files again.

Ente skips over files that have already been uploaded, so you can drag and drop the original folder or zip again after removing the files without thumbnails, and it'll only upload the files that are necessary.