>Now that I’ve made the plunge and updated to Windows 8.1, I’ve had no choice but to use IE11.

Initially, everything appeared to be fine, until I started to upload documents and mess about with the files. Compatibility mode didn’t manage to fix anything and I’ve always hated using that as a solution to a problem anyway so I thought that I’d find the solution to my problem. The problem seems to affect versions 2.5.3 and below and is definitely fixed from 2.5.4 onwards. This fix sorts out the old ‘Invalid JSON string’ error, TinyMCE loading errors and uploading file errors (through the previous two errors).

Looking around, the solution lies in how Moodle is actually detecting the browser that’s being used through the agent detection functions within lib/moodlelib.php and lib/tests/moodlelib_test.php. Simply replace these two files with the latest branch of your release and off you go.