Module name collision when different apps share module names

Frappe Framework Bug
1

I’ve encountered a critical issue with Frappe’s module mapping system and wanted to bring it to the community’s attention. I’ve also opened a GitHub issue for tracking.

GitHub Issue: Module name collision on different apps installed in different sites · Issue #34895 · frappe/frappe · GitHub

The Problem

When two independent apps declare a module with the same name in their modules.txt, Frappe’s setup_module_map() function overwrites the module→app mapping, causing the last app in apps.txt to “win.” This leads to ImportError when loading DocTypes that belong to the first app.

Quick Example

If ERPNext has a “Stock” module and a custom app also declares “Stock”:

  • Database says Stock belongs to ERPNext
  • In-memory cache says Stock belongs to custom app
  • Result: Frappe tries to load ERPNext DocTypes from the custom app → crash

Reproduction

  1. Create a custom app with a module named “Stock” in modules.txt
  2. Install ERPNext first, then the custom app
  3. ERPNext installation fails with ImportError: No module named 'customapp.stock.doctype...'

Root Cause

In frappe/__init__.py (lines 1678-1688), the mapping simply overwrites without conflict resolution:

local.module_app[module] = app  # Last app wins!

A warning is issued but doesn’t prevent the problem.

Discussion

Has anyone else encountered this? Any insights appreciated!

2

Unfortunately this is expected behavior. A decision was made to set module as global (they must be unique).

3

In my opinion “module” should be unique for each site (like doctype) but not at bench level that can manage multiple sites or apps.
For me it’s a design or a bug fault that should be solved

4

same issue here

1 Like
5

It certainly isn’t a bug (it’s a feature). Per-site would be impractical, but if the devs used some sort of dot-notation to include the parent directory/App or evaluate app+module it could reduce collisions.

Once you know they have to be unique, it’s not a deal breaker for most people.