Can not create file error on Assignment Module

Assignment allows file upload and online text. When Teacher clicks Grade button in Assignment, the receive following error:

Can not create file "1305/assignfeedback_editpdf/importhtml/307/onlinetext-onlinetext.html"
File:
...age/file_storage.php

Line: 1590

Stack trace:

Duplicate entry 'c673447ed6162145a7b373k8e8428a6b27c13579' for key 'mdl_file_pat_uix'INSERT INTO mdl_files (contextid,component,filearea,itemid,filepath,filename,timecreated,timemodified,userid,source,author,license,status,sortorder,filesize,contenthash,mimetype,pathnamehash) VALUES(?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)[array ( 0 => 1305, 1 => 'assignfeedback_editpdf', 2 => 'importhtml', 3 => '307', 4 => '/', 5 => 'onlinetext-onlinetext.html', 6 => 1472558696, 7 => 1472558696, 8 => NULL, 9 => NULL, 10 => NULL, 11 => NULL, 12 => 0, 13 => 0, 14 => 78, 15 => 'c202da428649a754c4f6dd5c8d9928813bcb41ca', 16 => 'text/html', 17 => 'c673447ed6162145a7b3779de84ss26b27c13579',)]Error code: storedfilenotcreated

The session for the user usually stalls forcing a clearing of browser cache/cookies to re enter site.

We are using Moodle 3.1.2.

I have tried disabling plugins, themes, creating a new course and assignment. I have tried not using the online text and just uploading a document. But when I go to post grades, it locks up browser. Our admin created this Moodle Tracker MDL-55859.