Cannot send iMessages on my Mac but can receive them

I just tried the one from cabrownfromottawa way up, i think on page 5 of this thread: https://discussions.apple.com/thread/7528581?answerId=33300061022#33300061022. If that doesn't take you there, here is a copy: So I tried everything on all 4 of these pages and none worked.  Finally I contacted Apple Support and after getting passed to a 2nd level, having them have me capture some logs and have them analyzed, I got it fixed.

Close all applications, specifically Messages

Reboot

Spotlight search for Keychain Access

Search in Keychain Access for - com.apple.facetime

Right click on and delete - com.apple.facetime: registrationV1

Reboot

Launch Messages

It certainly worked for me! Good luck!

Turns out that although in Settings on my iPhone were logged onto my main Apple ID, under >Messages >Send & receive the login Apple ID was an older ID I'd not used for a couple of years. Can't get my head around why or even how that works b/c I wouldn't have entered it and that ID no longer exists. All fixed & working now thanks to Linc Davis' response below.

THANK YOU @cabrownfromottawa for the following advice that was magical!

Close all applications, specifically Messages

Reboot

Spotlight search for Keychain Access

Search in Keychain Access for - com.apple.facetime

Right click on and delete - com.apple.facetime: registrationV1

Reboot

Launch Messages

I managed to fix it by searching for "imessage" in the Keychain. Four private keys showed up, deleted all four and iMessage started working. FaceTime not yet.

I've read the user forums often but have never responded. But I have to point out that for this problem, I tried several solutions offered in this thread, and this is the one that worked for me. Thank you!

Thank you so much!!! This was driving me crazy and everyone else's answer was so long and convoluted, I gave up!!!

Works like a charm now! I'd be at my computer, receive an iMessage and could not answer. It would always say...undelivered!

Thanks again!

Thank you so much!!! This was driving me crazy and everyone else's answer was so long and convoluted, I gave up!!!

Works like a charm now! I'd be at my computer, receive an iMessage and could not answer. It would always say...undelivered!

Thanks again!

I did this, tried to mark it helpful, and was not able to. It did work for me, perfectly. Happily, I had copied the instruction onto a sticky note, because today, several months later, I again was unable to send messages from my laptop. I went into keychain access as directed, and found that the com.apple.facetime had come back today, at 11:00 a.m. I followed the rest of the instructions, and it worked like a charm, again.

Praise Jeebus!!! This just worked for me after a torturous amount of frustration trying all the myriad of ways I'd read to fix this issue. Thank you, thank you!!! (And in a hysterical turn of events - this page just deigned to give me the dreaded red exclamation point saying my comment could not be posted. Oh, irony, you are not lost on me.)

Hi,

What have you tried so far ?

I am about to go Off line where I am and a reply may be nearer to 24 hours away.

8:29 pm Thursday; September 14, 2017

Hi,

You do realise that Text Forwarding is sending SMS items from and to the iPhone so it can pass it on via the phone's carrier service ?

iMessages are not SMS.

The Original Poster even says have can send SMS.

8:27 pm Thursday; December 14, 2017

Hi,

Try this Users Tip When the iMessages account will not Login

Particularly the last part about phoning Apple.

If you have two Active Receive At IDs such as the Apple ID and the iPhone Number you may well see "Sync" "Copies" (They are not Syncs as they are just sent to all registered devices - nor are they true copies but it is a simple way to think of the same Message being sent to the Apple ID and the iPhone Number)

9:12 pm Thursday; February 15, 2018

Try this:

1. go to Keychain Access app in the Utilities folder

2. under the File menu, choose *Lock Keychain "Login"*

3. go to the File menu again and choose *Unlock Keychain "Login"*

4. enter your password when prompted.

I'm on Sierra. I could receive messages on all my devices but after an OS security update I could not send or reply in Messages on my laptop. I finally got a useful error message (STKeychainErrorDomain error -25299) from a third-party app (Airmail3) indicating it had a problem accessing the Keychain. They sent me to a lengthy Apple help forum about rebuilding my Keychain. I started with the easiest possible suggested fix (above) and (ridiculously) it solved all my problems.

Hi,

You're welcome.

6:53 pm Monday; April 2, 2018

So I tried everything on all 4 of these pages and none worked. Finally I contacted Apple Support and after getting passed to a 2nd level, having them have me capture some logs and have them analyzed, I got it fixed.

Close all applications, specifically Messages

Reboot

Spotlight search for Keychain Access

Search in Keychain Access for - com.apple.facetime

Right click on and delete - com.apple.facetime: registrationV1

Reboot

Launch Messages

This worked immediately for me.

Hope this might help someone else!