When sharing with Twitter error occurs, it is because access to the platform has been invalidated.
There are two reasons for this:
1. The login and username has changed;
2. When Twitter detected a new access to another device.
To normalize, simply reconnect with the Postgrain.
a) Disconnect your Twitter profile on Postgrain:
b) Sign in to Twitter to revoke Repost app access:
Done. The page has been disconnected! Now you need to connect your Twitter account again.