A bit late to the party but with a working solution.
See the official Odoo documentation
https://www.odoo.com/documentation/17.0/applications/finance/accounting/customer_invoices/sequence.html#accounting-invoice-resequencing

Although it is for v17, it works as well in v16.
Not very intuitive at all!

I guess the invoicing sequence is not available in the "Sequences" list because changing an established invoice sequence has serious implications.

Now I'm trying to setup a new invoicing sequence using code for a new database after importing opening balances from a legacy ERP system.
Haven't figured that one out yet!

Hi Everyone,

I encountered the same issue on Odoo v16, and here's what worked for me:

1. I set the Customer Invoice sequence code as "account.move" (I found this by activating developer mode, opening a posted invoice, and checking the model name by hovering over the question mark next to the label on the header of the invoice UI).
2. Initially, the "Resequence" option was not visible under the action menu. However, after posting a draft invoice and selecting it in the Customer Invoice list view, the "Resequence" option became visible.
3. I posted a customer invoice, then posted and reset it to draft. This allowed me to edit the invoice number in the system to the format I desired (e.g., "INV/2024/04/00001" in my case).

These three methods worked for me and produced the desired result. I hope this helps someone in this forum facing a similar issue with Odoo. I also noticed that there was a customer invoice series automatically created under "Technical" -> "Sequences" for earlier number series alongside my new series, as I advised created as the first option.

For new Odoo users, please note that you only have to use any one method out of these three. I mentioned all findings that might help someone in some way.

Thanks,

CP

as the year renew after march my invoice should start with the new invoice no 001 but after applying resequence it shows an error that 001 already exist in previous year so you should start with the higher sequence number from the last save one.

Hello Paul, did you solve this problem with changing invoice sequence?

I still can't understand why this MAJOR FEATURE has been changed prior to Odoo v14... Without any proper documentation... The sequence settings were nice, now everything needs to be done manually every year before 1st of January... Very annoying, as I have subscriptions invoiced every first day of the month, which means when I didn't change it manually on the 31st of December at midnight, invoice sequence of 2024 will still be in 2023. Even more annoying when the fiscal year is not a calendar year!

For non accounting documents like quotations/orders that is ok, but for invoices, credit notes etc. it's not.

Or am I wrong and if I use a slash the for example 2023/CL/0999 will become 2024/CL/0001 automatically on 1/1/2024 ?

A good practices manual or some documentation on this would be nice, as it's confusing newer (v14+) versions of Odoo don't have sequence settings any more...

Hi Paul,

You can add any code name there or can leave it as blank.
The code field is usually used while creating sequences from backend codes with or without conditions.
We'll be using the next_by_code() method and pass in the code to fetch the corresponding sequence code and generate the sequence accordingly.

Regards