JetBrains/intellij-community · error · ConfigurationException

module.paths.validation.duplicate.content.error

module.paths.validation.duplicate.content.error

Error message

Content root ''{0}'' is defined for modules ''{1}'' and ''{2}''.
Two modules in a project cannot share the same content root.

What it means

Thrown by ModulesConfigurator when the exact same content root directory is assigned to two different modules (contentRootToModuleNameMap.put returns the previous, different module name). Two modules cannot share a content root — both would claim the same files for indexing, VCS and compilation — so the model update is rejected.

Source

Thrown at java/idea-ui/src/com/intellij/openapi/roots/ui/configuration/ModulesConfigurator.java:307

        if (!sourceRoots.add(root)) {
          throw new ConfigurationException(
            JavaUiBundle.message("module.paths.validation.duplicate.source.root.in.same.module.error", root.getPresentableUrl(),
                                 moduleName));
        }
      }
    }

    // Check for duplicate content roots across modules and map source roots to content roots
    for (ContentEntry contentEntry : contents) {
      final VirtualFile contentRoot = contentEntry.getFile();
      if (contentRoot == null) {
        continue;
      }

      // Check for duplicate content roots
      final String previousName = contentRootToModuleNameMap.put(contentRoot, moduleName);
      if (previousName != null && !previousName.equals(moduleName)) {
        throw new ConfigurationException(
          JavaUiBundle.message("module.paths.validation.duplicate.content.error", contentRoot.getPresentableUrl(), previousName, moduleName)
        );
      }

      // Map source roots to content roots and check for duplicates
      for (VirtualFile srcRoot : contentEntry.getSourceFolderFiles()) {
        final VirtualFile anotherContentRoot = srcRootsToContentRootMap.put(srcRoot, contentRoot);
        if (anotherContentRoot != null) {
          throwDuplicateSourceRootError(srcRoot, contentRoot, anotherContentRoot, contentRootToModuleNameMap);
        }
      }
    }
  }

  /**
   * Throws an appropriate error for duplicate source roots.
   */
  private static void throwDuplicateSourceRootError(@NotNull VirtualFile srcRoot,

View on GitHub (pinned to be881553f2)

Solutions

In Project Structure > Modules, remove the content root from one of the two modules named in the message
If the module is a duplicate import, delete the redundant module entirely
Fix the .iml files: ensure each <content url="..."> appears in exactly one module
For multi-project setups sharing sources, use one module with multiple source roots instead of two modules sharing one root

Example fix

<!-- before: two modules both declare content root $PROJECT_DIR$/shared -->
<!-- module-a.iml -->
<content url="file://$PROJECT_DIR$/shared"/>
<!-- module-b.iml -->
<content url="file://$PROJECT_DIR$/shared"/>

<!-- after: only module-a owns it -->
<!-- module-a.iml -->
<content url="file://$PROJECT_DIR$/shared"/>
<!-- module-b.iml -->
<content url="file://$PROJECT_DIR$/b-own-root"/>

Defensive patterns

Strategy: validation

Validate before calling

Map<VirtualFile, String> owner = new HashMap<>();
for (Module m : ModuleManager.getInstance(project).getModules()) {
  for (ContentEntry c : ModuleRootManager.getInstance(m).getContentEntries()) {
    VirtualFile root = c.getFile();
    if (root != null && owner.put(root, m.getName()) != null) {
      // two modules share this content root: remove it from one before apply
    }
  }
}

Try / catch

try {
  configurator.apply();
} catch (ConfigurationException e) {
  // message names both modules; drop the content root from the redundant one and retry
}

Prevention

Never copy a <content url="..."> block from one .iml to another
Import shared sources once; use a single module with multiple source roots instead
Run a periodic check that content root urls are unique across modules

When it happens

Trigger: Applying Project Structure changes where module A and module B each list the same directory as a content root; happens when the configurator validates editors in order and the second module's put() collides with the first's map entry.

Common situations: Importing two Maven/Gradle projects that both claim a shared parent directory; hand-edited .iml files copy-pasting a content url; splitting a module but forgetting to remove the old content entry; duplicate module import (same sources imported twice).

Related errors

AI-assisted analysis of JetBrains/intellij-community@be881553f2 (2026-08-14). Data as JSON: /api/errors/fe1ed78d6aee49db. Report an issue: GitHub.