FILES NOT UPLOADED. No error displayed, no rows added. HELP!!!!

[panwalker]

This appears to be an issue that has been popping up for years and never addressed, from my searches here and on devot.ee...

I can select multiple files to upload, it says it's uploading them, but nothing happens. No rows are created and no files are actually uploaded.

I have set the directories to 777 permissions, and I can upload single files through the regular Matrix file upload.

HELP??!!!

Using ExpressionEngine 2.7.0, testing on two different servers/hosts, same issue.

Looking in the Chrome tools, I see that the response returned to the addFiles function (line 156 of matrix_multi_upload.js) is NOT a json string as expected but instead just the following html (which explains why the error handling breaks, at least):

"

The following errors were encountered

• The action you have requested is invalid.

Return to Previous Page

"