What does the '400 Session Invalid' error mean?
The '400 Session Invalid' error is a temporary issue that occurs on Meta's side and requires no action from you.
What causes this error
This error originates from Meta's systems, not from your account or settings. It's an intermittent issue that can affect users from time to time.
How to fix this error
You have two options to resolve this Instagram connection error:
1. Wait 12 hours and try connecting your Instagram account again.
2. Connect your Instagram account to a Facebook page, then use the Facebook login for the Instagram integration with Post Bridge.