I get "character notes has been blocked from an action only available to the blizzard UI" while attempting to copy a players name.

This is a known issue with modifying the unit popup menus. Because it can interfere with other functionality, I added an option to turn off the updating of the menus. It is "Add Menu Items". It will remove the "Edit Note" option but should allow Copy Character Name to work. If you turn off the "Edit Note" menu item, you would need to use the slash command line options and the note UI to manage notes.

I will look into some more involved methods of modifying the menu. If I can get something better to work, I will push out a new release.

Many developers just avoid touching these menus. It has been like this for years so I don't think Blizzard plans to fix it to allow addon developers to add our own options without consequences.

The same happens when reporting a player away on bg. And sometimes when trying to enter a bg (won't enter until addon is disabled).
This is on Classic.

I am releasing an alpha version today that should resolve the issues. I will have a normal release in another day. If you can test it and find any issues, please let me know.

Thank you. I have tried it. The issue with reporting away players is fixed.

Spoke too soon. It still does get blocked when reporting sometimes.

Unfortunately, I believe the approach I am using now is probably the best method so it may not be possible to improve it.

Are you able to verify that it is Character Notes by disabling other addons? Sometimes the client reports the wrong addon in an error. Due to how libraries get loaded, it can blame an addon that gets loaded earlier than the actual offending addon.

Also is it exactly the same error? You may want to paste the error here and I can try to see if there is something I can figure out.

I am just trying to rule out other possibilities.

I enabled lua error reporting, and well, there aren't any. It just says "blocked".
Finally isolated, though. Fixed is reporting by right clicking on the portrait. But when reporting by clicking on name in chat, it's still blocked.

I can take a look at it. I may not be able to fix it though.

Oddly enough the right clicking on names in chat works on Retail. The new Copy Character Name option caused a similar issue before.