Well, if your addon has at least one template (options etc. count aswell), you could look for the creation date of the file in internal_data/code_cache. That might help the admin to get on the right track.
Well, if your addon has at least one template (options etc. count aswell), you could look for the creation date of the file in internal_data/code_cache. That might help the admin to get on the right track.
How many admins do you run across that are willing to give you FTP or PHPMyAdmin access? I don't run across many at all. For some it's like pulling teeth just to get XenForo admin access to debug a problem on their site.
Having the install/upgrade dates on the add-on page would just help immensely in quickly establishing what happened when.
In that case ask the admin to do it. If that's not possible, go to an addon template, make a fake edit and have a look at the template history. The first date is the install or upgrade date I suppose.