Alert says "iTunes can not be opened while it is being updated." but nothing ever changes

For the past week I have been getting this message when I try to open iTunes.

It doesn't matter how long I wait, nothing ever changes. If I reboot my computer and try to open iTunes immediately after startup, iTunes will open normally. But eventually this same message will appear again after closing iTunes and trying to open it again later. I am running El Capitan 10.11.6 on a late 2012 iMac. Has anyone else experienced this or a similar issue and does anyone know of way to resolve this problem?

Solution 1:

This thread talks about checking for OS updates, and also trying to start the computer in safe mode: https://discussions.apple.com/thread/7416168?start=0&tstart=0

If you don't have any OS updates to do, you might as well just download a new iTunes app and install a fresh copy: https://www.apple.com/itunes/download/