Thanks for the reply. This is a fairly default install, which means that my $wgUploadPath value is just the “images” subdirectory- that seems to be the default. And indeed, the directory exists (with the permissions mentioned before).
Just to check, I then set $wgUploadPath manually, and confirmed that the wiki is looking for the image URL in what should be the right place. Unfortunately, the problem persists.
EDIT: Found the problem! Apparently, some previous work early on resulted in an incorrect HTACCESS file in this folder. Removing that allowed uploads to work as expected. Thanks again!
One helpful piece of information: the error message is actually an error “500 internal error”- the 404 message simply referred to a problem locating an error document. The error document is pasted below:
[quote='500 internal error page]
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, email@example.com and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.[/quote]