Duplicate invoice generated at the same time

[Julia Nunes]

We identified a case where Killbill generated two invoices for the same account and same target date.
Both invoices have status = COMMITTED and were created at the exact same timestamp, but with different created_by values. This suggests that two different processes might have triggered invoice generation simultaneously.

Example:

• Account: 00058ba4-b7ff-457c-9347-53335c1bae62

• Target Date / Invoice Date: 2025-08-30

• Invoices generated:

"id" : "33494534-876e-4a8d-a57e-c92e0e2f3a5e", "created_by" : "Next Billing Date", "created_date" : "2025-08-31T01:35:28.000Z"

"id" : "a12ce4e7-e440-41aa-bcf1-26ae671a413b", "created_by" : "SubscriptionBaseTransition", "created_date" : "2025-08-31T01:35:28.000Z"

Impact:

• Duplicate invoices created for the same account and date.

• Double charging the customer.

Question to the Killbill team:

• What is the recommended way to handle this case ?

• How can we prevent this duplication from happening again ?

[karan bansal]

Hi Julia,

Could you please query both the above invoices with this endpoint and share the results. It would also be helpful if you can list down the steps to reproduce this issue as well as sample catalog used. Please also share Kill Bill logs if possible.  

Regards

Karan

[Julia Nunes]

  Please find attached the query result with the duplicated invoices

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[karan bansal]

Hi Julia,

Could you please share the data that I have originally requested. I need to see the invoice items. It would also be helpful if you can share the other data as well like the steps to reproduce this issue and sample catalog used. 

Regards

Karan

[karan bansal]

Hi Julia,

These invoices indeed look like duplicates. Were these invoices auto generated by Kill Bill OR was there any manual trigger?  Do you happen to have Kill Bill logs from the time these invoices were generated? 

Has this issue happened again for this account OR is it happening for any other account as well? 

Regards
Karan

On Thu, Dec 11, 2025 at 8:26 PM Julia Nunes <nune...@gmail.com> wrote:

Hi, do you have updates?

Em seg., 1 de dez. de 2025 às 10:04, Julia Nunes <nune...@gmail.com> escreveu:

Hello,  here is the result of the two duplicated invoices attached

Em qua., 24 de set. de 2025 às 00:16, karan bansal <karanba...@gmail.com> escreveu:

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[Julia Nunes]

Hi Karan,

Thanks for checking.

Based on the Kill Bill Core data, these invoices were automatically generated by Kill Bill, with no manual trigger involved.

For the same account and billing period, we identified two invoices created at the exact same timestamp, but with different system triggers.
This was confirmed using the query below:

SELECT * FROM killbill.invoices i WHERE i.account_id IN (:accountIds) AND i.invoice_date IN ( SELECT invoice_date FROM killbill.invoices WHERE account_id = i.account_id GROUP BY invoice_date HAVING COUNT(*) > 1 );

Query result (same account and invoice date):

{ "record_id": 3623297, "id": "33494534-876e-4a8d-a57e-c92e0e2f3a5e", "account_id": "00058ba4-b7ff-457c-9347-53335c1bae62", "invoice_date": "2025-08-30", "target_date": "2025-08-30", "currency": "BRL", "status": "COMMITTED", "created_by": "Next Billing Date", "created_date": "2025-08-31T01:35:28.000Z" }, { "record_id": 3623298, "id": "a12ce4e7-e440-41aa-bcf1-26ae671a413b", "account_id": "00058ba4-b7ff-457c-9347-53335c1bae62", "invoice_date": "2025-08-30", "target_date": "2025-08-30", "currency": "BRL", "status": "COMMITTED", "created_by": "SubscriptionBaseTransition", "created_date": "2025-08-31T01:35:28.000Z" }

As shown above:

• One invoice was created by Next Billing Date

• The other was created by SubscriptionBaseTransition

• Both were generated at 2025-08-31T01:35:28 UTC

This indicates that the next billing processing and a subscription phase transition occurred simultaneously, resulting in duplicate invoice generation for the same billing date.

At the moment, we are validating:

• whether this behavior occurred again for this same account, and

• whether there are similar cases affecting other accounts.

We are also checking the availability of Kill Bill logs around the invoice creation timestamp and will share them as soon as they are confirmed.

Best regards,

[karan bansal]

Hi Julia,

Yes, getting the logs would be helpful. Could you please also share the server configuration as well as the db details. 

Regards

Karan