One of the users for my install of EE is getting an error saying “The file you are attempting to upload has invalid content for it’s MIME type.” sometimes when she tries to upload a PDF.

What would cause this?

Double check that the mimes.php file has ‘pdf’  =>  ‘application/pdf’, in it.

It does have that in there. Might it have something to do with her user or computer?

I’m not sure. Can you upload a pdf file?

Is it one particular file?

I just tried to upload the same file that was registering the mime type error and received this message:

“An error was encountered while attempting to replace the file. Please make sure your file directory is writable.”

I assume it’s talking about the uploads folder, which is indeed writable (set to 777).

But is the file itself set to 666?

Rename the original file, and try again.

The file was set to 777, but I went ahead and removed it and then uploaded the new version.

It went through successfully.

I also tried replacing another pdf that was on the site and it went through successfully without me deleting it.

But now to see if the client can upload.

I had a similar if not identical problem. Could not upload PDFs when logged into the CP except as the superadmin. Found the solution on another thread. Need to turn off XSS Sanitizing in Admin > System Preferences > Security and Session Preferences.