Running the maintenance script (Manual:FAQ#…are some of my images not showing up after an upgrade) does not fix the issue.
We face the same problem after upgrading to 1.30: Thumbnails are shown as broken images though they are correctly rendered on server side. The developer console of chrome reveals the following error messages:
Failed parsing 'srcset' attribute value since it has an unknown descriptor.
Dropped srcset candidate "/uploads/thumb/xxx.png/450px-xxx.png"
Failed parsing 'srcset' attribute value since it has an unknown descriptor.
Dropped srcset candidate "/uploads/thumb/xxx.png/450px-xxx.png"
GET https://aaa.bbb.ccc/5x 404 (Not Found)
Is this a known bug, can anybody confirm this behaviour or is there any solution?