This error occurs when Time+Billing reaches the maximum invoice number of 999999 and cannot assign the next number. Manual numbering may already be enabled, but the system still blocks posting until the sequence is corrected.
Identify the next valid invoice number
Log in to Time+Billing, then go to View, Invoices (Finalised).
Review the existing invoice numbers.
Go to Reports, Debtors Transactions, Invoice Transactions to view the full invoice history.
Identify the last correct number in your intended sequence.
Note: You may see large gaps in numbering. Use the next logical number in your firm’s sequence.
Restore invoice posting
Go to View, Invoices (Finalised).
Locate the invoice numbered 999999 and select Delete. Note: If a receipt is attached, delete the receipt first from View, Receipts.
Go to Options, Invoice/Receipt Numbers.
Under Invoice:
Select Manual Numbers.
Enter the next valid number in the Next Number field.
Click OK.
Go to Input, Invoice (WIP) or Invoice (No WIP) and complete as required.
Click Post Final.
In the Verify Invoice Number window, confirm or enter the correct number.
Click OK.
Return to automatic numbering
After posting the invoice:
Go to Options, Invoice/Receipt Numbers.
Clear the Manual Numbers checkbox.
Click OK.
Time+Billing will continue assigning invoice numbers automatically from the updated sequence. If required, reprocess any receipts against the new invoice number.