A user reported an issue where the user notes modal couldn’t be closed via the X button or ESC key, persisting even in safe mode. Initial testing by JammyDodger and RGJ couldn’t reproduce the issue, prompting pfaffman to investigate further. After moving the thread to Product Support, pfaffman confirmed the culprit was the deprecated “guest gate” plugin, thanking RGJ for the help pfaffman. Stephen noted that similar issues arise from “plugin hoarding” — installing many plugins “just in case,” even when disabled, which can still affect performance and stability. pfaffman suggested that a two-container setup with a graphical dashboard (like dashboard.literatecomputing.com) could help users manage plugins more safely and avoid such issues.
To replicate:
Clicking the X to close the modal does nothing. Hitting ESC does nothing. Reloading the page seems to be the only way to close the modal.
This site has a few crazy plugins, but the problem persists in safe mode.
I have just given this a go, and it works here on Meta?
Cannot repro… maybe you should look at those crazy plugins?
Feel free to PM me the hostname and I’ll be happy to have a look.
OK. I moved this to Support. This guy insists that he hates custom plugins but also insists that his site does things that require plugins. 
I will crank up the staging site and start removing stuff.
It was the guest gate plugin. Thanks, @RGJ!
I’ve looked at a couple of customer sites recently which had some truly egregious examples of plugin hoarding - mores than certain Wordpress sites. The need to rebuild when installing a plugin had convinced them to install practically everything they could find on the off-chance they would one day need them, and unlike WP they didn’t appreciate that even disabled plugins can have an impact on stability and performance.
Interesting. A two-container installation an a dashboard that would let you graphically add/remove plugins could be a good solution for those people.