Manual:$wgThumbnailEpoch

Files and file uploads: $wgThumbnailEpoch
If rendered thumbnail files are older than this timestamp, they will be re-rendered on demand as if the file didn't already exist.
Introduced in version:1.6.0 (r11945)
Removed in version:still in use
Allowed values:timestamp (string)
Default value:'20030516000000'

Details edit

If rendered thumbnail files are older than this timestamp, they will be re-rendered on demand as if the file didn't already exist. Update if there is some need to force thumbs and SVG rasterizations to re-render, such as fixes to rendering bugs.

For a quick copy-paste you can use the following line, which was generated using {{CURRENTTIMESTAMP}}:

$wgThumbnailEpoch = 20240319030412;

If you are using a Unix-like system you can get the current date by entering the following on the command-line:

date +%Y%m%d%H%M%S

See also edit