Customer is looking for a list of all possible errors expected in Manage Pending Transactions page

Our customer is looking for a list of all possible errors that one can expect in pending transactions page for internal training purposes, would you be able to provide such list of possible errors?

If not all, would you be able to at least share the most common possible errors one might encounter in the pending transactions page?

That would really be appreciated.

Thanks,

Tabish Shivani