I just installed InvoicePlane on my server and I cannot create new invoices or quotes. Creating clients does work fine, though. I checked the JS console and there were no errors. This happens in every browser I’ve tried, even with no extensions installed.
I just figured out the problem: CloudFlare’s “optimizations” for JS made it not work any more. If anyone has this problem, disable CloudFlare’s Rocket Loader and Java Script minification / optimization.