Big Sur - Messages not starting

I have the same problem like amirqasemi74. I tried to reset Messages and bring it to a clean state, but nothing worked for me.

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Facetime and Messages also stopped working on my MacBook after I updated to Big Sur 11.1 on 12/22/2020. I tried this fix found online and it worked. Now my Facetime and Messages are working again on my MacBook.

On your iphone:
1) Go to Settings - Messages app – Preferences – uncheck iMessage on icloud
2) Sign out of your Apple ID account
3) Sign back in with your Apple ID & password
4) Go back to Settings - Messages app - Preferences - enable iMessage on icloud again.

Then try to open Facetime or Messages on your MacBook. They should work again. Mine did, not sure why or how but they did.
Good luck!

I simply force-quit Messages and then restarted my MacBook from the Apple menu, and my Messages started working again.

I too had this happen. I tried everything I could find on the web and had no luck. I finally broke down and called Apple Support. Apparently in my case, there was a block placed on my account. It seems to have happened at the same time I updated to Big Sur. I asked how it happened and was told it could have been my number was reported by spam or something. Oddly enough, it only happened on my macbook and my iPad, not my iPhone. So when in doubt and you find nothing that fixes the problem.. Give em a call! :)

I had this issue as well. Icon jumping, but then not opening. Still received notifications of messages but app would not open. I tried deleting plist files, starting in safe mode, opening the calendar first, and eventually reinstalled Big Sur. Nothing worked. I called apple support and they recommended holding the option key while clicking on the icon to open. It worked.

Netsmith's method of opening calendar first and then opening messages worked for me. What a weird bug and fix...

I also have been experiencing this issue after updating to macOS 11.1.

Launching the Mac Calendar application first before messages also worked for me.

I followed these steps:

On your iphone:
1) Go to Settings - Messages app – Preferences – uncheck iMessage on icloud and Forward Messages to my Mac.
2) Sign out of your Apple ID account
3) Sign back in with your Apple ID & password
4) Go back to Settings - Messages app - Preferences - enable iMessage on icloud and Forward Messages again.
5) Rebooted Mac...SUCCESS!

There is an unnecessary and confusing step in the solution below, which warrants a correction.

Namely: there is no Preferences option on iPhone for the messages APP

Here is the correct process: (this is for BIG SUR ONLY, though the instructions are for iOS 14)

On your iPhone:
1) Go to Settings - Messages APP
2) Uncheck iMessage - this automatically unchecks what is called Send & Receive, NOT "Forward Messages to my Mac."
3) Then, recheck it back to Green
This technically resets the synch between the iPhone and your recently updated machine to Big Sur, making the steps below unnecessary.

• ************

2) Sign out of your Apple ID account
3) Sign back in with your Apple ID & password
4) Go back to Settings - Messages app - Preferences - enable iMessage on icloud and Forward Messages again.
5) Rebooted Mac...SUCCESS!

I followed what mbwins10 said. I opened messages, then force quit. I shut down my computer and then booted it up again. All the messages that had appeared in messages on my iPad now appeared in messages on my MacBook air - big sur as well. Thanks to mbwins10!

when i try to run messages in macOS Big Sur, The application hangs and
doesn't respond, I checked terminal when trying to open the exe file and
recieve the following error:

Invalid absolute dimension, must be > 0.0. NOTE: This will be a hard-assert soon, please update your call site.

Laurmac nailed it in this post:

https://developer.apple.com/forums/thread/652842?answerId=658366022#658366022

... hold down the option key while clicking Messages in the Dock. It seems to me to be related to the Messages window trying to come up but the coordinates are off and the app is offscreen, but the app is depending on isVisible in order to complete the process of launching. That would do exactly what we are seeing.

This was a recommended fix from Apple... my guess is that all the workarounds we're finding are enough to reset the x/y coordinates of the window so that it comes up onscreen and visible. 🙃

This happens to me. For some odd reason, if I open Calendar first, then Messages will open. Otherwise, Messages just won't respond or open. Very strange.

This worked right up for me.
I wonder what's causing the issue.
Mac OS 11.2.3 (not beta)

This is still an issue in the public release, did anyone find a solution? Restart fixes it but it comes back regularly and is hella annoying.