I assume that’s a typo and actual version is 1.8.7?
I’m not sure why and how you ended up with 2 notificationView modules, you should most likely remove the second one (id 20).
I assume you’re referring to this topic? Notification Widget and old thumbnails - #4 by dan
If you executed that sql command then it would explain why you have 2 notificationview modules now, since you had this modules already (as you should, it is system module) you definitely should not need to run the command to add a duplicate of it to the modules table.
I’d certainly not expect to see such error on a fresh 1.8.7 docker installation.
If after removing the duplicate you will still get that error, could you please go through Report Fault Wizard and share the relevant log messages for those errors with us?