What causes "Module short name cannot be empty" in JetBrains/intellij-community?

Change the module name so the last dot-separated segment is non-empty (e.g. 'mygroup.mymodule' instead of 'mygroup.')

JetBrains/intellij-community · error · ConfigurationException

error.short.name.module.cannot.be.empty

error.short.name.module.cannot.be.empty

Error message

Module short name cannot be empty

What it means

Thrown from ModuleConfigurable.checkName() when renaming a module to a full name whose shortened (group-stripped) form is empty. Module names may use dotted group paths like 'group.sub.name'; ModuleGrouper.getShortenedNameByFullModuleName removes group prefixes, and a name consisting only of group separators (e.g. a trailing dot) leaves an empty short name, which is invalid.

Source

Thrown at java/idea-ui/src/com/intellij/openapi/roots/ui/configuration/projectRoot/ModuleConfigurable.java:68

    if (StringUtil.isEmpty(name)) return; //empty string comes on double click on module node
    if (Comparing.strEqual(name, myModuleName)) return; //nothing changed
    try {
      modifiableModuleModel.renameModule(myModule, name);
    }
    catch (ModuleWithNameAlreadyExists moduleWithNameAlreadyExists) {
      //do nothing
    }
    myConfigurator.moduleRenamed(myModule, myModuleName, name);
    myModuleName = name;
    myConfigurator.setModified(!Comparing.strEqual(myModuleName, myModule.getName()));
    myContext.getDaemonAnalyzer().queueUpdateForAllElementsWithErrors();
  }

  @Override
  protected void checkName(@NotNull String name) throws ConfigurationException {
    super.checkName(name);
    if (myModuleGrouper.getShortenedNameByFullModuleName(name).isEmpty()) {
      throw new ConfigurationException(LangBundle.message("error.short.name.module.cannot.be.empty"));
    }
    List<String> list = myModuleGrouper.getGroupPathByModuleName(name);
    if (list.stream().anyMatch(String::isEmpty)) {
      throw new ConfigurationException(LangBundle.message("error.names.of.parent.groups.cannot.be.empty"));
    }
  }

  public ModuleGrouper getModuleGrouper() {
    return myModuleGrouper;
  }

  @Override
  public ProjectStructureElement getProjectStructureElement() {
    return myProjectStructureElement;
  }

  @Override
  public @NotNull Module getEditableObject() {

View on GitHub (pinned to be881553f2)

Solutions

Change the module name so the last dot-separated segment is non-empty (e.g. 'mygroup.mymodule' instead of 'mygroup.')
Avoid leading/trailing dots in module names

Defensive patterns

Strategy: validation

Validate before calling

String shortName = ModuleGrouper.getShortenedNameByFullModuleName(newName);
if (shortName.isEmpty()) reject("module short name cannot be empty");

Try / catch

try { moduleConfigurable.checkName(name); } catch (ConfigurationException e) { /* show message, keep editor open */ }

Prevention

Never end a module name with '.'
When generating grouped names, assert the last dotted segment is non-empty

When it happens

Trigger: Renaming a module in Project Structure to a value whose short name after group stripping is empty, such as '.' or 'a.'. ModuleGrouper.getShortenedNameByFullModuleName(name) returns an empty string.

Common situations: Typo in module rename (trailing dot, only dots); pasting a name with an invisible trailing separator; scripted renames generating malformed dotted names.

Related errors

AI-assisted analysis of JetBrains/intellij-community@be881553f2 (2026-08-14). Data as JSON: /api/errors/afd72ebcafccfc96. Report an issue: GitHub.