JetBrains/intellij-community · error · CodeGenerationException

Class not found:

Error message

Class not found: 

What it means

AsmCodeGenerator.getComponentClass catches ClassNotFoundException from InstrumentationClassFinder.loadClass and rethrows it as CodeGenerationException('Class not found: ' + className). The GUI Forms bytecode generator could not locate a component class on the instrumentation classpath while compiling a .form.

Source

Thrown at java/compiler/forms-compiler/src/com/intellij/uiDesigner/compiler/AsmCodeGenerator.java:244

  public byte[] getPatchedData() {
    return myPatchedData;
  }

  static void pushPropValue(GeneratorAdapter generator, String propertyClass, Object value) {
    PropertyCodeGenerator codeGen = myPropertyCodeGenerators.get(propertyClass);
    if (codeGen == null) {
      throw new RuntimeException("Unknown property class " + propertyClass);
    }
    codeGen.generatePushValue(generator, value);
  }

  static InstrumentationClassFinder.PseudoClass getComponentClass(String className, final InstrumentationClassFinder finder) throws CodeGenerationException {
    try {
      return finder.loadClass(className);
    }
    catch (ClassNotFoundException e) {
      throw new CodeGenerationException(null, "Class not found: " + className);
    }
    catch(UnsupportedClassVersionError e) {
      throw new CodeGenerationException(null, "Unsupported class version error: " + className);
    }
    catch (IOException e) {
      throw new CodeGenerationException(null, e.getMessage(), e);
    }
  }

  public static Type typeFromClassName(final String className) {
    return Type.getType("L" + className.replace('.', '/') + ";");
  }

  class FormClassVisitor extends ClassVisitor implements GetFontMethodProvider {
    private String myClassName;
    private String mySuperName;
    private final Map<String, String> myFieldDescMap = new HashMap<>();
    private final Map<String, Integer> myFieldAccessMap = new HashMap<>();

View on GitHub (pinned to be881553f2)

Solutions

1. Add the missing library/module dependency so the component class is on the compile classpath
2. Rebuild the module containing the component (class may simply not be compiled yet); a full Rebuild often clears it
3. Fix the class name in the .form file if the component was renamed/moved (check the form XML's component class attribute)
4. If it appears only after upgrades, clear build caches (System|Local History unrelated; use File > Invalidate Caches) and rebuild

try { Class.forName(className, false, loader); } catch (ClassNotFoundException e) { /* resolve dependency before compiling forms */ }

catch (CodeGenerationException e) if message starts with 'Class not found:': read the class name, verify module dependencies, then rebuild

When it happens

Trigger: Compiling/instrumenting a form whose component (or a class referenced by it, e.g. a custom bean or nested form's class) is not on the finder's classpath: missing dependency JAR, class not yet compiled, wrong class name in the .form XML.

Common situations: Building a module before its dependencies; custom Swing components in a library not added to the module dependencies; obfuscated/renamed classes after a refactor; forms referencing classes moved to another module; running instrumentation with a stale compile output.

Related errors

• Unsupported class version error:
• Attempt to compile nested form with no nested form loader sp
• No binding on root component of nested form
• Recursive form nesting is not allowed
• Invalid input: {input}

AI-assisted analysis of JetBrains/intellij-community@be881553f2 (2026-08-14). Data as JSON: /api/errors/8c6ef2ae68076ec2. Report an issue: GitHub.