Okay, if you’re getting the ‘metadata mismatch’ error, but it isn’t interfering with your ability to use the engine, I wouldn’t worry about it. However, this thread implies that the metadata mismatch would prevent you from cooking projects.
If that is a potential problem, first you should try Verifying your engine install. In the Launcher, click the little down-arrow next to “Launch” underneath the engine version you’re using. If Verifying the engine doesn’t work, you may be forced to wipe the “appdata\local\unreal engine” folder and reinstall, as described in the thread. That should only be a last resort, however.