# Exceptions - `HTTPException` and `WebSocketException`

These are the exceptions that you can raise to show errors to the client.

When you raise an exception, as would happen with normal Python, the rest of the execution is aborted. This way you can raise these exceptions from anywhere in the code to abort a request and show the error to the client.

You can use:

* `HTTPException`
* `WebSocketException`

         * @param request the request data
         * @param exceptionList the list of exceptions that occurred during retries
         */
        void onRequestEnd(FaultTolerantClient client, RequestData request, List<Exception> exceptionList);

        /**
         * Called when an exception occurs during a request attempt.
         *
         * @param client the fault-tolerant client

        Exception exception = assertThrows(Exception.class, () -> {
            new KerberosRelevantAuthData(emptyToken, keys);
        }, "An exception should be thrown for an empty token.");

        // The exception could be PACDecodingException or NullPointerException
        assertTrue(exception instanceof PACDecodingException || exception instanceof NullPointerException,

 */
package jcifs;

import java.io.IOException;

/**
 * Base for all checked exceptions used by this library
 *
 * @author mbechler
 *
 */
public class CIFSException extends IOException {

    /**
     *
     */
    private static final long serialVersionUID = 7806460518865806784L;

    /**
     * Constructs a CIFS exception with no detail message.
     */
    public CIFSException() {

    @DisplayName("Test default constructor creates exception with null message")
    public void testDefaultConstructor() {
        // Create exception with default constructor
        TransportException exception = new TransportException();

        // Verify the exception is created and has no message
        assertNotNull(exception);
        assertNull(exception.getMessage());
        assertNull(exception.getCause());

        // When
        SmbException exception = new SmbException(ntStatus, false);

        // Then
        assertTrue(exception.getMessage().toLowerCase().contains("sharing") || exception.getMessage().toLowerCase().contains("violation")
                || exception.getMessage().toLowerCase().contains("used") || exception.getMessage().toLowerCase().contains("being used")
                || exception.getMessage().toLowerCase().contains("process"));

     *
     * @param level the severity level of the message
     * @param message the message to be logged
     * @param error the associated exception, or null if not applicable
     */
    void log(@Nonnull Level level, @Nonnull String message, @Nullable Throwable error);

    /**
     * Logs a debug message without an associated exception.
     *

{* ../../docs_src/handling_errors/tutorial002.py hl[14] *}

## Install custom exception handlers { #install-custom-exception-handlers }

You can add custom exception handlers with <a href="https://www.starlette.io/exceptions/" class="external-link" target="_blank">the same exception utilities from Starlette</a>.

Let's say you have a custom exception `UnicornException` that you (or a library you use) might `raise`.

/**
 * Base class for all maven exceptions carrying {@link BuilderProblem}s.
 *
 * @since 4.0.0
 */
@Experimental
public abstract class MavenBuilderException extends MavenException {

    /**
     * The collection of problems associated with this exception.
     */
    private final ProblemCollector<BuilderProblem> problems;

    /**
     * Constructs a new exception with the specified message and cause.

    void mockInteraction_stubsThrow_andVerifiesInvocation() {
        // Arrange: Since SmbUnsupportedOperationException is a checked exception (extends IOException),
        // we need to use a method that can throw checked exceptions or wrap it in a RuntimeException
        @SuppressWarnings("unchecked")
        Supplier<String> supplier = mock(Supplier.class);