Bug: "Duplicate IPN not allowed" error when unlocking an existing part

[bvweerd]

Please verify that this bug has NOT been raised before.

• I checked and didn't find a similar issue

Describe the bug*

When editing an existing part that has been locked and trying to unlock, saving the form throws a "Duplicate IPN not allowed in part settings" error. Other settings while keeping the part locked seem to be working

Settings:
Allow Duplicate IPN: FALSE
Part Revisions: TRUE

Steps to Reproduce

1. Create a part with revisions enabled (e.g. IPN: AS0001234, Revision: 4)
2. Create a new revision of that part via the Revisions tab → Duplicate Part (IPN: AS0001234, Revision: 5, linked via "Revision of" field)
3. Lock the new revision (Revision 5)
4. Unlock the part to make an edit
5. Press Save

Expected behaviour

The part saves successfully.

Deployment Method

Docker

Version Information

InvenTree-Version: 1.3.2
Django Version: 5.2.13
Commit Hash: a60e85b
Commit Date: 2026-05-05
Commit Branch: null
Database: django.db.backends.postgresql
Debug-Mode: True
Deployed using Docker: True
Platform: Linux-6.1.0-40-amd64-x86_64-with-glibc2.41
Installer: DOC
Active plugins: [{"name":"InvenTreeBarcode","slug":"inventreebarcode","version":"2.2.0"},{"name":"BOM Exporter","slug":"bom-exporter","version":"1.1.0"},{"name":"InvenTree Exporter","slug":"inventree-exporter","version":"1.0.0"},{"name":"Parameter Exporter","slug":"parameter-exporter","version":"2.0.0"},{"name":"InvenTreeEmailNotifications","slug":"inventree-email-notification","version":"1.0.0"},{"name":"InvenTreeUINotifications","slug":"inventree-ui-notification","version":"1.0.0"},{"name":"InvenTreeCurrencyExchange","slug":"inventreecurrencyexchange","version":"1.0.0"},{"name":"InvenTreeMachines","slug":"inventree-machines","version":"1.0.0"},{"name":"InvenTreeLabel","slug":"inventreelabel","version":"1.1.0"},{"name":"InvenTreeLabelMachine","slug":"inventreelabelmachine","version":"1.0.0"},{"name":"Altium BOM Importer","slug":"altium-bom-importer","version":"0.2.0"},{"name":"Altium Connector","slug":"altium-connector","version":"0.3.0"},{"name":"Custom BOM Exporter","slug":"custom_bom_exporter","version":"0.2.2"},{"name":"Brother Labels","slug":"brother","version":"2.0.5"},{"name":"IPNGenerator","slug":"ipngen","version":"0.2"},{"name":"SolidWorks BOM Importer","slug":"solidworks-bom-importer","version":"0.2.0"},{"name":"Tree View","slug":"tree-view","version":"0.1.1"}]

Try to reproduce on the demo site

I tried to reproduce

Is the bug reproducible on the demo site?

Reproducible

Relevant log output

2026-05-27T08:50:25.185794Z [warning  ] request_finished               [django_structlog.middlewares.request] code=400 ip=10.0.0.1 request='PATCH /api/part/XXXX/' request_id=00000000-0000-0000-0000-000000000000 user_id=1
2026-05-27 08:50:25,185 WARNING {'code': 400, 'request': 'PATCH /api/part/XXXX/', 'event': 'request_finished', 'ip': '10.0.0.1', 'request_id': '00000000-0000-0000-0000-000000000000', 'user_id': 1, 'timestamp': '2026-05-27T08:50:25.185794Z', 'logger': 'django_structlog.middlewares.request', 'level': 'warning'}
Bad Request: /api/part/XXXX/
2026-05-27 08:50:25,186 WARNING Bad Request: /api/part/XXXX/
10.0.0.1 - - [27/May/2026:08:50:25 +0000] "PATCH /api/part/XXXX/ HTTP/1.1" 400 54 "https://inventree.example.com/web/part/XXXX/details" "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:151.0) Gecko/20100101 Firefox/151.0"

[SchrodingersGat]

Refer to these two settings:

[bvweerd]

But how is it then that you're allowed to make a revision item with the same IPN, although the allow duplicate IPN is false, but not unlock the part?

[SchrodingersGat]

@bvweerd can you please provide a clearer step-through of what you are seeing, with screenshots / screencast?

[bvweerd]

@SchrodingersGat

In the demo site the behavior is erroneous but a bit different in the last step, but: I duplicated the first part, filled out 2 for revision:
(Note that I cannot verify the duplication setting in the admin interface of the demo site)

Set the newly created part to "locked", and save.

Edit the part again, and remove locked:

In my own instance, it says in the last step:

[gunstr]

I also had the need to validate that the combination of IPN and Revision is unique and we discussed that in #4618 some years back. The solution we agreed by then was to use a plugin for such validation. I have used it since then and it works well. You can find the plugin here.

A part name uniqueness is validated for the combination of Name and Revision and it could make sense to do the same for the IPN and Revision also in core - but I think that for IPN there are potentially other use cases where IPN should always be unique. If something should be implemented in core the settings should likely cover all three options:

1. No validation - IPN can be duplicated
2. IPN should always be unique
3. IPN and Revision combined should be unique

[matmair]

Not a fan of making core more complicated if plugins already solve the problem; every new setting for an edge case makes the app more imitating and easier to miss-configure

[SchrodingersGat]

I cannot reproduce this issue locally either - although from that 500 error I think there is likely an issue with the demo server