I tried the Beta 10.11.1 update from the GM last night but it complained about the iCloud Password after the update and had issues signing into Messages for some reason. I tried a few things(reboot, log out and in iCloud) but went ahead and reinstalled the GM release from the "purchased tab" and Messages worked again. Anyone seen this issue with 10.11.1?
Edit: someone else has this issue: https://forums.developer.apple.com/thread/19370
Edit: someone else has this issue: https://forums.developer.apple.com/thread/19370
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