Once e-way bill for sales invoice is created, there are certain restrictions for sales invoice updates.
- You cannot update Contact, Invoice items and Sales invoice number
- Only Transportation details can be updated once e-way bill is created
However, to make this even easier, Hisab has provided certain automated ways to handle this situations.
- System will ask user to whether cancel earlier e-way bill and generate new, or just cancel earlier one.
- If earlier e-way bill is not cancellable or has expired, you can still update sales invoice, but it will be marked as "Not in Sync". As e-way bill and sales invoice details doesn't match.

Whenever e-way bill that is created and sales invoice's data doesn't match due to any override, it will be marked as "Not in Sync" and is shown as warning sign. This is supposed to not happen in ideal scenario.