Hi @1rameez, welcome to the PBC! From your screenshot it appears you are using the Andriod app, I would first suggest to make sure the app is updated.
What has helped me with the "validation error" prompt was to clear the cache on the app, stop and restart the app.
Settings->Apps->Pinterest->Storage-> clear cache (*not data*). Then go back and force stop the app, reopen the app.
I really hope that makes sense 🙂