Q: iMessage on Mac has names highlighted in red and will not sync with my phone

Hello er1234, this could be caused because your mac does not have Yosemite on it yet. If you want you can download the demo version or wait until it comes out.

There is no demo, ignore that advice, it's wrong.

There is a beta test (if you wish to partake in a test) but using a beta on your main machine is a very bad idea.

Wait for Yosemite (Oct 21)

Hi,

On or around the 9th of September some people started to report that all their Contacts were showing as Not Registered when they tried to send Messages.

Red Name in the "To" spot tend to mean the iMessages contacts details are off line.

In some cases the info is genuine such as an iPhone being shut off or out of service area. (Ends users tend to be using iPhone only)

Similar things can happen if a Mac is only using the Apple ID and is off-line.

At present there is no fix to the issue about all the Contacts appearing to be Not Registered.

I have posted feedback to Apple via the Feedback pages and posted in the Lounge as a "New Technical Issue" in the hope things will get moving on this.

It could be that everyone will have to wait for an update.

It is unclear if there will be another to Mavericks as Yosemite is on the horizon.

Apple have only ever released two Standalone Updates to iChat or Mavericks and the last was at iChat 3.

I would recommend NOT upgrading in an attempt to "Fix" this.

The demo of Yosemite seems to still call the version there "Messages 8" which means it is not an Update of the app.

I would also recommend fixing issues before any Update or Upgrade unless the update says it is specifically to fix the issue your have.

9:55 pm      Tuesday; September 23, 2014

Hi Ralph,

I was able to text anyone, including non iPhone users from my iMac via Yosemite until two days ago.  It was great!  Now, many contacts are in red.  It seems that I can only use the texting function for iPhone users.  Did Apple change that?

Thanks!

Hi,

Apple have not changed anything  or at least not deliberately.

What we have come to believe is that there are several issues that require Apple Support staff intervention.

The Errors are sort of layered.

There are these 4 as documented here FaceTime, Game Center, Messages: Troubleshooting sign in issues - Apple Support

Then is the Visible error messages that reads like this:-

This is obviously well known to some people and can only be fixed (for Free) by contacting Support.  If the Level 1 person does not know what you are talking about or wants to charge you as you have no Apple Care cover ask to speak to a Level 2 person.

I tend to refer to this as Error 5.

The Next error is when the app looks like it is logged in.  There is no error messages on any sort but all Contacts get the "not registered" messages on the Mac version even when the ID is sending Messages on other devices.

We have suggested that people delete the Keychain Item dealing with the iMessages Login.

Or Deleting the .plist for the same.

None seem to work.

That leaves contacting Apple Support.

You have to persuade them to check your Apple ID with the iMessages server as in Error 5.

This can be a little more difficult to get them to do as the app appears to be working.

8:17 pm      Monday; December 22, 2014