Fixing KCFinder Thumbnails That Stop Generating After a Site Move

One of the more frustrating post-migration bugs in Evolution CMS is a file browser that still uploads images but no longer creates previews. In the original case, KCFinder stopped generating JPG and PNG thumbnails after a site was moved from a test account to a production account on the same host.

The obvious checks were already in place: the .thumbs directory existed, permissions were open, and the site itself still worked. That is why this kind of failure is easy to misread as a pure filesystem problem when it is often a version and cache consistency problem instead.

What to check first

• Make sure the KCFinder cache directory really belongs to the current site copy and is writable by the active PHP user.
• Delete stale generated thumbnails and test again with a freshly uploaded image.
• Verify that the production copy is running the same Evolution CMS build and KCFinder-related files you tested locally.
• Re-upload a new image through KCFinder rather than relying only on files copied over from another environment.

Why updates can fix it

In the source case, the issue was resolved after updating Evolution CMS to the latest build, removing the broken image set, and uploading the files again through KCFinder. That points to a combination of outdated file manager code and stale thumbnail state rather than a permanent hosting limitation.

If you see this behavior after a move, treat it as a migration consistency issue: update the CMS first, clear generated thumbnail artifacts, and rebuild previews from clean uploads. That sequence is usually faster than endlessly chasing permissions that already look correct.