Messages: "Your message could not be sent"

I know this is an old thread, but I recently had this problem on MacOS High Sierra and got all the way up to a senior person at Apple Customer Support to solve it.

There's a really solid troubleshooting guide for this error here.

Ultimately, what worked for me was to run this command from Terminal:

sudo rm /Library/Preferences/com.apple.apsd.plist

Hi,

Interesting link.

Some things listed in item 9 don't exist.

The "madrid" item does not have the name it has in earlier versions of the OS.

Deleting some of those .plists also stops the processes running making step 10 obsolete.

Many of the steps are covered here When the iMessages account will not Login

Step 5 makes the Location issues look more difficult list the Apple Europe Time Server and the standard Apple Pic for Apple's headquarters as the actual Location.

Step 13 shows the poster removing two Auth Tokens meaning they are deleting two Apple ID items which in turn suggests they have a deeper issue than one ID blocked by the iMessages Servers.

If the account(s) is/are not logging in then it will make no difference whether you delete the singing and Encryption items.

Seeing that iMessages is yet to be an iCloud items I don't see the reason for Step 12.

That said some items like the IDS Auth Tokens are copied from the Login Keychain to the iCloud one.

7:39 pm Thursday; January 4, 2018

Hi,

I take it that GamePigeon and Stickers are Add-ons to the Mac version.

I know there is a plugin folder fro this sort of thing like the ChatFX add-on for iChat but I had not been looking for any.

(I looked in the App Store with no luck for "Messages Add-ons" or "GamePigeon" as all one word. I was looking from a Mac)

It sounds like something is not compatible.

If it is an iOS Messages addon the Mac version may not cope with it.

7:25 pm Monday; December 26, 2016

Hi,

I did a second search via Google.

https://itunes.apple.com/gb/app/gamepigeon/id1124197642?mt=8 has this written top left under the logo

This app is designed for both iPhone and iPad

7:36 pm Monday; December 26, 2016

Hi,

It's not an Apple problem.

The developer has not written things a way that is compatible with the Mac versions (I say versions as there will be people still using the El Capitan and Yosemite versions if not earlier ones).

Expanding some of the info on the App Store info shows this:-

If you are using a beta version of iOS10 and GamePigeon has suddenly stopped working for you - then you should update your iOS to the latest stable version: Settings>General>Software Update. If you are still experiencing problems - make sure you send us an email.

There appears to be no hint to make it compatible with the Mac version.

The "Support" link only goes to the developers site about the app with no support hints whatsoever.

8:10 pm Monday; December 26, 2016