I get blocked while uploading images by my hosts’ security and we get that sorted then I can’t upload an image. I keep getting a “HTTP error” or a 404/page not found. I try other sites on the server and I can upload images just fine. (I was trying with different images.) I try reinstalling WordPress files. I try deactivating plugins. I tried creating new .htaccess files. I even restarted my computer (last resort!). I tried using the standard theme.
And what was the problem? The client had commas and apostrophes in the file name.
That was it. Between Saving for Web and uploading to WordPress most file name abominations get sorted by the software. Perhaps a different version of PHP is more forgiving.. but file naming is always a bane when receiving files from a non-programmer.
To get an “HTTP error” message for a poorly named file sent me down too many different rabbit holes. Why not a message that says something like “Bad file name.” Would have saved me hours and not a little distress.