While backing up all my sites it fails on 8 out of close to 30 total websites. Mostly wordpress installs.
The error message for all these is the same. All 8 are wordpress installs. But so are 95% of the sites on this server.
.. upload failed! Error in call to API function "files/upload_session/append:2": Bad HTTP "Content-Type" header: "application/x-www-form-urlencoded". Expecting one of "application/octet-stream", "text/plain; charset=dropbox-cors-hack". (performed 3 attempts)
Its pretty clear what that means. Just not sure why it might be happening.
What other error logs or info do we need to help trouble shoot this.