Interesting, I've not seen this error before. It is strange that clearing the cache should return errors from another unrelated task - this suggests there might be a deeper problem in your AtoM installation. Can you please remind me about your installation environment? Specifically:
- Have you followed our recommended installation instructions?
- If yes, are you using Ubuntu 14.04 or Ubuntu 16.04?
- If no, what changes have you made in your installation?
- What version of PHP do you have installed?
Are you by chance mid-way through an upgrade to 2.4 or something? Because the file referenced in the error message ( lib/task/export/csvExportTermUsageTask.class.php ) does not actually exist in AtoM 2.3.1! It was added for the 2.4 release. See for example:
Can you also check the full installation version listed in Admin > Settings > Global?
Anything else you think we should know about your AtoM installation, and the actions that lead up to the error, are welcome!
One thing you could try is manually deleting the cache contents, restarting services, and seeing if that resolves the issue. The cache directory should be just below your root AtoM directory, make sure you change to your root AtoM directory (which, if you followed our recommended installation instructions, is located at /usr/share/nginx/atom) before running the following: