JetBrains/intellij-community · error · IncorrectOperationException

Cannot create class in invalid package: '{qualifiedName}'

Error message

Cannot create class in invalid package: '{qualifiedName}'

What it means

Thrown by JavaDirectoryServiceImpl.checkCreateClassOrInterface() when the directory's package qualified name is non-empty but not a valid Java qualified name (PsiNameHelper.isQualifiedName fails). The directory itself exists in a package whose name is malformed, so no class can be created in it. Note the name identifier and file-creation checks have already passed at this point.

Source

Thrown at java/java-impl/src/com/intellij/psi/impl/file/JavaDirectoryServiceImpl.java:215

                             FileTemplateManager.getInstance(project).internalTemplateToSubject(templateName), templateName);
  }

  @Override
  public void checkCreateClass(@NotNull PsiDirectory dir, @NotNull String name) throws IncorrectOperationException {
    checkCreateClassOrInterface(dir, name);
  }

  public static void checkCreateClassOrInterface(@NotNull PsiDirectory directory, String name) throws IncorrectOperationException {
    PsiUtil.checkIsIdentifier(directory.getManager(), name);

    String fileName = name + "." + JavaFileType.INSTANCE.getDefaultExtension();
    directory.checkCreateFile(fileName);

    PsiNameHelper helper = PsiNameHelper.getInstance(directory.getProject());
    PsiPackage aPackage = JavaDirectoryService.getInstance().getPackage(directory);
    String qualifiedName = aPackage == null ? null : aPackage.getQualifiedName();
    if (!StringUtil.isEmpty(qualifiedName) && !helper.isQualifiedName(qualifiedName)) {
      throw new IncorrectOperationException("Cannot create class in invalid package: '"+qualifiedName+"'");
    }
  }

  @Override
  public boolean isSourceRoot(@NotNull PsiDirectory dir) {
    final VirtualFile file = dir.getVirtualFile();
    final VirtualFile sourceRoot = ProjectRootManager.getInstance(dir.getProject()).getFileIndex().getSourceRootForFile(file);
    return file.equals(sourceRoot);
  }

  @Override
  public LanguageLevel getLanguageLevel(@NotNull PsiDirectory dir) {
    return JavaPsiImplementationHelper.getInstance(dir.getProject()).getEffectiveLanguageLevel(dir.getVirtualFile());
  }

}

View on GitHub (pinned to be881553f2)

Solutions

1. Rename the offending source directory (and any parent segments) so every segment is a valid Java identifier: letters, digits, $, _, no hyphens/spaces/dots.
2. Check the module's source roots (Project Structure > Modules > Sources) and unmark directories that are not real packages (e.g. resources, generated non-Java output).
3. If the folder name is fixed by tooling, move the Java code into a properly named package directory and adjust the package statement.
4. Use PsiNameHelper.getInstance(project).isQualifiedName(name) on the computed package name before attempting creation.

Example fix

// before: source root layout
src/my-pkg/Main.java   // package my-pkg; -> invalid
// after
src/mypkg/Main.java    // package mypkg;

PsiPackage pkg = JavaDirectoryService.getInstance().getPackage(directory);
String qname = pkg == null ? null : pkg.getQualifiedName();
if (qname != null && !qname.isEmpty() && !PsiNameHelper.getInstance(project).isQualifiedName(qname)) {
  // invalid package directory; do not attempt class creation
}

try { JavaDirectoryServiceImpl.checkCreateClassOrInterface(dir, name); } catch (IncorrectOperationException e) { /* directory is in an invalid package; prompt user to fix source layout */ }

When it happens

Trigger: Calling createClass/checkCreateClassOrInterface on a PsiDirectory whose package name contains illegal characters or segments: a source folder named 'my-pkg', a directory with spaces or keywords like 'int'/'class' as segment names, or nested directories forming 'com..x'.

Common situations: Importing a project where source roots contain folders that are not valid Java identifiers (hyphens, dots in folder names, leading digits); resources accidentally marked as sources; multi-release or generated directories with odd names; packages named with Java keywords.

Related errors

• {0} is not a valid package name
• Cannot create {0} - incorrect {1} template.
• Cannot create class-file
• Cannot create package '{0}' in source folder {1}
• Invalid package name: {0}

AI-assisted analysis of JetBrains/intellij-community@be881553f2 (2026-08-14). Data as JSON: /api/errors/a908c44c381d0364. Report an issue: GitHub.