mod_progress treats 2xx(!=200) return code as error
"mod_progress.c" in the line 316 does a check against HTTP status code 200 only.
All HTTP codes in the form 2xx should indicate a success, as it's defined in the standard.
I find the 204 code to be particularly useful in a file upload, cause that makes browsers to not load a new page after the upload.
Please consider the trivial change of making a number between 200 and 299 to indicate success (or maybe only 4xx and 5xx to indicate error).
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