From my own findings this is where I got to, broken down into the 3 types of error messages:
1) "
Error: Netatmo: Invalid/no data received..." Changing App, Client id, password/token, Domoticz Beta does not clear this error. Only solution seemed to be restoring a previous backup of the Domoticz database. How far back you need to go to resolve this error is not clear! Once this error is cleared, I was then able to restore back to my latest database.
2) "
Error: Netatmo: Error connecting to Server..." I needed to setup a new "app" in dev.netatmo.com and enter the details into the Domoticz Hardware tab to clear this.
3) "
Error: Netatmo: No access granted, check credentials..." Nearly there! Re-enter into Domoticz Hardware tab latest login / token detail as was always needed by Netatmo.
So depending on the error will give a guide of the next steps, which may well be in the error order above
Hopefully the Domoticz developers will update the Netatmo plugin in line with Netatmo's new security "features" soon.