This question may be related to a resolved thread.
This recently just started happening to me. As a superadmin with XSS filter turned off I cannot upload any file regardless of size or type. I don’t have a disk space limit on my server and I have increased the size of my php execution time. The permissions on all of folders are 777 as they should be. Neither Pixel & Tonics Assets nor native EE file manager will upload. I can upload via ftp fine as well. And synchronizing files works fine too.
EE: 2.3.1
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