How to fix Hangouts not working for one gmail account My Hangouts had two email accounts associated with it. One stopped working. I tried deleting and re-installing Hangouts. I tried deleting and reinstalling the email account that was not working with Hangouts. 

Now when I try to add this second email account to Hangouts, I get the error message that the account already exists on the device. 

I did delete that email account and before adding it via the phone's accounts manager, I tried to add it from Hangouts. It then added it as an email account but not associated with Hangouts.
Sorry - I got it fixed. I tried deleting the email account and then before re-adding it, I restarted the phone. Then when I added the account to Hangouts it worked.