I just wanted to change the logo I had uploaded. So I went to /admin/config/logo, removed the current logo, and tried to upload the new one. It failed: POST https://example.discourse.group/uploads/complete-external-upload 400 (Bad Request)
It works when I scroll down and click submit to save after deleting the old logo before uploading the new one. It also works to drop the new logo without deleting the old one, but I didn’t try that at first because as long as there is a logo in place, the field doesn’t say I can do that.
I also tried uploading a new logo, deleting that, and uploading another one, which also fails:
Okay, actually the upload works. When you delete the old logo, upload a new one, ignore the error, and submit the changes, you will see the new logo. So, what does the error tell me, and why are the buttons disabled afterwards when it magically still works?