Upon loading FL Studio one day, I got the following error message: the connection to this plugin was lost. Of course a bunch of other plugins were working, just not that specific one (in this case it was EWQL Pianos).
A few solutions to this were either trying to re-scan the plugins with re-verification, or running it in the wrapper--which doesn't make sense since all 3rd party plugins run in the fruity VST wrapper. However what nobody seems to mention is that you have to be cautious whether or not you're running x86/x64 FL Studio or x86/x64 VST plugins. While they do cross over, sometimes 32-bit plugins will have issues on the 32-bit host or vice versa. Of course the problem is that I accidentally launched FL Studio x86 instead of 64-bit version that I usually do; and because EWQL didn't program their software very intuitively, I never bothered to get the x86 version of their plugin working, so only the 64-bit version works for me, and always needs the 64-bit version of FL Studio.
Keep that in mind if you ever get this error and potentially can't figure out what's inecessantly triggering it.