This is very similar to Matrix File Upload not displaying contents of directory, upload silently fails
I've just begun to work on an existing MSM site.
I set up some new upload directories, added them to my bootstrap array.
I had the faded upload button, etc. When I updated my indexes, it returned to normal but the upload still just silently failed.
I updated Assets to the latest version because I read in the changelog "Failed uploads now display a proper error message."
Upon trying the upload again, I had to laugh... the alert simply said "undefined".
When I try to upload to an existing upload directory, I can't upload either, but the error says: "Could not upload the file - server returned an unexpected response. Please check the server settings."
In my web developer toolbar, the network tab shows a 200 OK POST to
ACT36 in my DB is Assets_mcp/upload_file.
All the folders have 777 permissions.
I believe all the file paths are correct because I can see files in Assets, I just can't upload.
What am I missing?