Please update invoice voucher number sequence to resolve this issue. This is a common issue if you are using continues number sequence, you can un tick the continues and the system will create new unused voucher number. Or go to status and remove the list of free voucher numbers.
Please let us know if this helps.
Thanks,
André Arnaud de Cal...
291,965
Super User 2025 Season 1
Martin Dráb
230,836
Most Valuable Professional
nmaenpaa
101,156