After updating my Mozilla Firefox browser to version 52, I am not able to use ChemDraw Plugin. How can I fix this?
Just like it happened with Google Chrome back in 2015, Mozilla Firefox has removed the support for all NPAPI plugins with their 52 release, including the one for ChemDraw.
The only workaround is to use only Internet Explorer with the plugin or you can try installing Firefox ESR 52 (32 bit version). The old NPAPI plugins will continue to work in the Firefox ESR (Extended Support Release) 52, but will eventually be deprecated in ESR 59.