Solution: Getting macOS Messages to work with Google Chat / Talk / Hangouts in High Sierra
The Messages application wasn't working for me on macOS and I was wanting it to work with my Google Chat / Talk / Hangouts service. It appears that with macOS High Sierra a workaround is required. After struggling to get it going I finally got it going after some searching on the Internet and trying a couple of supposed fixes. What ended up working for me were the instructions on https://forums.macrumors.com/threads/gtalk-messages-solution-found-high-sierra.2073393/ with a couple of tweaks. The tweaks were required to support 2FA which is enabled on my account. The instructions, repeated here so that I can find them again if required and to assist others having the same problem, are as follows: Go to System Preferences / Internet Accounts and delete your google account. Open Terminal and run the following commands (Warning: This will delete your history!): find ~/Library/Preferences -name "*iChat*" -delete rm -rf ~/Library/Caches/com.apple.Messages rm -rf...