Two things to try:
1. Toggle wifi off and on (or on and off).
2. Open your phone browser and log in to chess.com then try to return to the app.
I've had to do do one or the other in the past to resolve. Note that in both instances, I killed the app first.
Let me know if either of the above help.
If you deactivated facebook, that happens to the accounts that are logged in via facebook.
We can get this problem fixed by going to the app settings and clearing all data.After clearing all data ..go back to the app and you will find the log in button in top right corner of the app.This way you can login again,it works fine for me this way...
Log out and login again. It worked for me.
What to do when invalid login token supplied ?
https://support.chess.com/article/822-what-does-invalid-login-token-detected-mean
Ps. it worked fine yesterday.