iMessage not working on Big Sur

Check your login / local_items keychain. I was having this issue and it was ultimately because I changed my macOS password a few weeks before upgrading to big sur. It looks like when iMessage / Facetime try to login with the Apple ID, they get stuck because the keychain was created / locked with the *old* macOS password. So try this (from https://support.apple.com/en-us/HT202860):

1. Open Keychain Access, which is in the Utilities folder of your Applications folder. 
2. Choose Preferences from the Keychain Access menu, then click the Reset My Default Keychain button in the preferences window. After you enter your new password, Keychain Access creates an empty login keychain with no password. Click OK to confirm.
3. 
   
4. If you don't see a Reset My Default keychain button, close the preferences window and select the “login” keychain from the left side of the Keychain Access window. Press the Delete key, then click Delete References.
5. 
   
6. Choose Log Out from the Apple menu to return to the login screen.
7. Log in to your account using your new password. Your account password and login keychain password now match again.

I am having the same problem, after I updated I was not able to sign in at all, I sign in, and about a few moments later it prompts me to sign in again. I re-installed macOS Big Sur, and it did not resolve my issue. Even restarting the Mac, and not using it for a few days didn't fix my issue. I thought it would be fixed in a patch, but there hasn't been a patch since Big Sur came out. I would love to fix this.

I had this same experience and Mac Support was not able to help me, although they did give me an idea of where to look. Apparently, my contacts were not working correctly with iMessage once I updated (and reinstalled, and wiped my machine, etc., etc.). I found this fix in another thread and it worked to get iMessage working again and also showing the names instead of just the phone numbers.

https://discussions.apple.com/thread/8340892

Now the only problem I have is that quite often my messages are failing to send. Still working on that one.

So when I tried to boot messages this morning in Big Sur, wouldn't open, got a kernel panic, but the notifications for them are showing.

Tried these steps to no avail:

1. boot to safe mode
2. reset nvram
3. moved to trash the .plist file in Library
4. reset SMC ( even thought I didn't expect this to help as it is used for power issues)
5. booted to recovery, ran Disk Utility (first aid) on all containers
6. reinstalled macOS from Recovery

Issue still persists, I understand that there are bugs, so hoping that Apple sends out an update to fix these bugs.

Messages on my 2018 Mac mini have not worked since upgrading to Big Sur. When I open the app and log in the wheel spins and eventually I get a message that says "An Unknown Error Occurred".

I am an IT Professional and a Mac user since 1985 - also a big fan of Apple.

I have been working with Apple Support for 20 days on this issue. They call me back when they have another thing to try. Here's what We've done.

Keep in mind it still doesn't work after trying all of these things:

• Booting into Safe Mode
• Reinstalling Big Sur
• Completely wiping the Mac, restoring it to the OS it shipped with, (Mojave) and reinstalling Big Sur
• Deleting the Messages DB items in the Library
• Deleting the Login Keychain and creating a new one

The person I've been working with at Apple is excellent. The issue is she has to wait for the engineers to get back to her with another thing to try.

I've spent many hours on the phone with her and many hours on my own trying to solve this issue.

If anyone has been able to resolve this issue, please let me know. Thank you.

How did you resolve the issue? I tried all of the above and wasn't able to get it to work:

• Booting into Safe Mode
• Reinstalling Big Sur
• Completely wiping the Mac, restoring it to the OS it shipped with, (Mojave) and reinstalling Big Sur
• Deleting the Messages DB items in the Library
• Deleting the Login Keychain and creating a new one

Thank you!

So I too have been having the same issue since updating to BS. I have updated on 2 separate iMacs >> one device works like a charm, and the other iMessage is a "brick"

I tried the usual fixes >>

Starting with the APP itself: Sign out/ sign in of Apple ID; sync/unsync; untick 'enable icloud messages";

Supporting services: listed here >> proxy under wifi

System >> reinstall BS via recovery mode

All unsuccessful on the brick device.

The fact that one device works and the other doesn't would seem to debunk the idea that it is associated with the Apple ID being associated as SPAM and someone turned off at the Apple server. If that were the case, then the AID/iMessage shouldn't work on either device.

What I did find finally seemed to help on the Brick device:

1. Delete some of the imessages that have a fail, and re-start the thread with the individual
2. Voila... it worked... not scientific, but at least a respite from the pains of not having ability to send messages from my desktop.

So, if you don't mind deleting the text thread that is not allowing you to send the message >> try deleting and restarting new text thread with same individual, and see if that helps?

It worked for me... either lucky or just a Christmas miracle

Good luck and stay safe.

Update: Messages on my Mac mini has been working for about 5 hours now with no issues.

Here's what was done to fix the problem with the help of a very capable Apple Support Professional:

Create New Administrator Account (TestUserName)

• Created a new administrator account on the Mac mini (TestUserName)
• Logged out of my current account (MyUserName) out of iCloud on the Mac mini (Which is an administrator account)

Log in to the New Administrator Account on the Mac (TestUserName)

• Logged into the new administrator account on the Mac mini (TestUserName)
• Ignored all messages to add my AppleId during set-up (Clicked on Set Up Later)
• Logged into Messages using my existing iCloud ID name/password after set-up
• Logged into iCloud using my existing iCloud ID name/password

Test Messages on Mac mini

• Sent a text message from the new administrator account (TestUserName) logged into my iCloud account to a fellow iPhone / Messages user (Worked)
• Sent a text message from the new administrator account (TestUserName) logged into my iCloud account to friend who uses an Android device (Worked)
• Sent a Message from my iPhone to myself (Worked and displayed on the Mac)
• Turned on "Enable Messages in iCloud" in Messages Preferences for TestUserName
• Important Note: It took a long time to sync (30-45 minutes) - I did not touch the Mac until it was done with the sync

Final Clean-Up

• Deleted my current account from the Mac mini (MyUserName)
• Renamed TestUserName to a different name (MyNewUserName)
• Notes:
  • I did not use the same name as previous MyUserName for MyNewUserName
  • I didn't not change any of the folder settings, names or paths for MyNewUserName that were set-up or created for TestUserName

Potential Causes of the Issue

• Keychain Issue?
  • I deleted the Login and Local Items from the Keychain and turned off iCloud Keychain sync while trying to resolve this problem during prior attempts to resolve the issue
    • That did not help
  • Maybe it was corrupt Keychain value, certificate or account setting for MyUserName?
  • Maybe it was an issue with my iCloud Keychain?
  • Maybe an issue with something trying to block network traffic for Messages for MyUserName?
  • Maybe an issue with my AppleId and/or secure encryption used for iCloud Keychain?

In any case all of this happened after my upgrade to Big Sur. I had no issues before the upgrade.

I'm thankful for the Christmas Miracle!

I had this issue for a week. Only when I used Safari did I realise what the issue was! I could not connect to any website. All Apple products did not work for me, Facetime, iCloud, Messages, even the app store was sometime intermittent. It also prevented me from installing Sophos End Point correctly, as it was blocking the autoupdate that installs the extension.

Somehow the settings in Safari/ as part of the Big Suck update toggled the network Proxies settings 'Auto Proxy Discovery'.

Just go to the wifi icon, click Network Preferences, unlock the padlock, enter your Mac OS user account password, click Advanced, select the Proxies Tab and then untick Auto Proxy Discovery.

Your welcome.

You mean "You're Welcome"? Yeah, no that didn't help. Big Suck is funny tho.. my Auto Proxy Discovery was already unticked.

But, still iMessage not working. I guess the joke is on us.. brand new computer or brand new OS and things don't work. Oh well, waiting on a fix or update.

So, imsg now works on my macbookpro... What I did...

1) Go to Messges app - Preferences - uncheck imessage on cloud

2) Sign out

3) Sign back in with your Apple ID password

4) Enable the settings again

Hope it starts working for you guys as well. It was so annoying when it didnt sync in real time...

Best wishes

-Farah

I had the same issue and talked with customer support.

HERE IS WHAT HAPPENED.

There is a chance your Apple ID was reported by someone as SPAM. So your further signing in was blocked on the server side. You have to talk to them to remove the blocking.

As a few others reported, restarting the machine fixed the problem for me.

I had tried logging out of iMessage to address a different problem (you cannot use arrow keys to move around the message input field if Messages is on anything OTHER than the primary monitor, and “Use keyboard navigation to move focus between controls” is enabled in the Shortcuts tab of the Keyboard preference pane), at which point I was unable to log back in to iMessage thanks to the mysterious “unknown error” error.

Thanks for leading me in the right direction. My Auto Proxy Discover was not ticked, but then I noticed that I had about 70 networks checked and I cleared them all out just because I am OCD and messages and FT started working again. I have no idea if that was actually the problem. Just glad it's working! :)

Thank you david.ross392 and knightvsbishop,

I reset my login keychain and deleted the local items keychain. Restarted and logged back in.

Unfortunately it didn't work.

knightvsbishop, I don't have any failed messages so I'm unable to try what you've suggested.

A Christmas miracle would be nice. I've been working on this for over 20 days now. Apple hasn't been able to resolve the issue and I still have an open ticket with them.

If you guys or others have ideas, I'm willing to check them out.

This is an incredible pain.

Thanks again.