If Google Health shows Linked in MyNetDiary but synchronization fails with an unexpected error, the connection may have been set up with a Google account that does not yet contain your Fitbit data.
This can happen during the Fitbit-to-Google Health migration if your Fitbit account has not yet been moved to that Google account, or if you signed in with a different Google account.
To fix it, first make sure your Fitbit data has been moved to the Google account you want to use with Google Health. Then Verify or Unlink the broken connection in MyNetDiary and link Google Health again with the correct Google account.
If you previously used Fitbit
Make sure your Fitbit account and data have been moved to the Google account you want to use with Google Health.
If needed, follow Google's instructions for moving Fitbit to a Google account.
After the move is complete, open Google Health settings in MyNetDiary and select Verify. If the broken connection remains, unlink Google Health, then link it again and sign in with the Google account that contains your Fitbit data.
If Google Health still shows Linked but will not sync
Waiting for the next scheduled synchronization will not repair a broken Google Health connection.
Open your Google Health settings in MyNetDiary and use Verify. If the connection still cannot sync, unlink Google Health and link it again using the Google account that contains your Fitbit data.
Make sure you use the correct Google account
If you have more than one Google account, make sure you sign in to Google Health with the account where your Fitbit data was moved.
Your MyNetDiary account email does not need to be the same as your Google account email. What matters is that the Google account connected to Google Health contains your Fitbit data.