ol-301 QuickBooks might occur due to interrupted communication or issues with the information. You might get a dialogue window stating that an error message has been sent with the error code OL-301. Follow these troubleshooting  steps to resolve this complication:

• Before you proceed, create and save a backup of the company file

• Verify the account balances and transactions, and check that the QB account is reconciled with the bank account

• Delete and remove any pending bank alerts

• If there is Windows firewall blockage or internet settings restrict QuickBooks issues, bypass them

Finally, if the QuickBooks error OL-301 persists, you should consider resetting the connected accounts in QuickBooks