junit-team/junit5 · error · IllegalStateException

Unsupported AnnotatedElement type for @TempDir: %s

Error message

Unsupported AnnotatedElement type for @TempDir: %s

What it means

IllegalStateException from the internal TempDirDeletionStrategy.IgnoreFailures.descriptionFor(AnnotatedElement) helper, which only knows how to describe Fields and Parameters. If the AnnotatedElement passed in is neither (e.g. a Class, Method, Constructor, or Module), the method cannot produce a human-readable description and throws. It is an internal (@API INTERNAL) safeguard indicating an unsupported element context reached the @TempDir cleanup path.

Source

Thrown at junit-jupiter-api/src/main/java/org/junit/jupiter/api/io/TempDirDeletionStrategy.java:139

			return DeletionResult.builder(tempDir).build();
		}

		private void logWarning(AnnotatedElementContext elementContext, DeletionException exception) {
			logger.warn(exception, () -> "Failed to delete all temporary files for %s".formatted(
				descriptionFor(elementContext.getAnnotatedElement())));
		}

		@API(status = INTERNAL, since = "6.1")
		public static String descriptionFor(AnnotatedElement annotatedElement) {
			if (annotatedElement instanceof Field field) {
				return "field " + field.getDeclaringClass().getSimpleName() + "." + field.getName();
			}
			if (annotatedElement instanceof Parameter parameter) {
				Executable executable = parameter.getDeclaringExecutable();
				return "parameter '" + parameter.getName() + "' in " + descriptionFor(executable);
			}
			throw new IllegalStateException("Unsupported AnnotatedElement type for @TempDir: " + annotatedElement);
		}

		private static String descriptionFor(Executable executable) {
			boolean isConstructor = executable instanceof Constructor<?>;
			String type = isConstructor ? "constructor" : "method";
			String name = isConstructor ? executable.getDeclaringClass().getSimpleName() : executable.getName();
			return "%s %s(%s)".formatted(type, name,
				ClassUtils.nullSafeToString(Class::getSimpleName, executable.getParameterTypes()));
		}
	}

	/**
	 * Standard {@link TempDirDeletionStrategy} implementation that recursively
	 * deletes all files and directories within the temporary directory.
	 *
	 * <p>Symbolic and other types of links, such as junctions on Windows, are
	 * not followed. A warning is logged when deleting a link that targets a
	 * location outside the temporary directory.

View on GitHub (pinned to f070c699a0)

Solutions

1. If you wrote a custom AnnotatedElementContext, ensure getAnnotatedElement() returns the actual Field or Parameter annotated with @TempDir.
2. Do not reuse the internal IgnoreFailures.descriptionFor helper for arbitrary element types; build your own description string.
3. File a JUnit issue if this occurs with stock @TempDir field/parameter injection — it indicates a framework bug.

Example fix

// before: custom context returns a Method
public AnnotatedElement getAnnotatedElement() { return method; }
// after
public AnnotatedElement getAnnotatedElement() { return parameter; }

AnnotatedElement ae = ctx.getAnnotatedElement();
if (!(ae instanceof Field || ae instanceof Parameter)) {
    throw new IllegalArgumentException("Unsupported element: " + ae);
}

static boolean isSupportedTempDirElement(AnnotatedElement ae) {
    return ae instanceof Field || ae instanceof Parameter;
}

When it happens

Trigger: An extension or custom TempDirDeletionStrategy calls descriptionFor(...) with an AnnotatedElement that is not a java.lang.reflect.Field or java.lang.reflect.Parameter. Normal @TempDir usage (field or parameter injection) never hits this; it requires an unusual element-context implementation.

Common situations: Writing a custom TempDirDeletionStrategy / AnnotatedElementContext that returns a Method or Class as its annotated element; integration code that reuses the internal descriptionFor helper; an edge case where a constructor-level element is misclassified.

Related errors

• @TempDir field [%s] must not be declared as final.
• Can only resolve @TempDir %s of type java.nio.file.Path or j
• Failed to create default temp directory
• temp directory must be a directory
• temp directory with non-default file system cannot be inject

AI-assisted analysis of junit-team/junit5@f070c699a0 (2026-08-11). Data as JSON: /api/errors/1fb1d39dc7010add. Report an issue: GitHub.