If we have not made all accounting setups properly then the system will post values to related temp accounts.
By default system will not allow posting values into temp accounts.
If any entry throwing the error as "Does not allow to post in temporary ledger" then
We have to enable the add-on function to post values into temp account ledger.
To enable:
Go to Home > Control Panel > Manage Account > Add-Ons > Enable "Allow Posting in Temporary Ledger"
Save/update the settings and try to post the item transactions.
Read more about adding opening balances.