JetBrains/intellij-community · error · BuildException

Prompt is null

Error message

Prompt is null

What it means

IdeaInputHandler is the Ant InputHandler that pipes Ant <input> task prompts to the IDE UI via packets. Ant's InputRequest.getPrompt() should always carry the prompt text; if it is null the handler cannot build a meaningful request and fails fast with BuildException("Prompt is null").

Source

Thrown at java/java-runtime/src/com/intellij/rt/ant/execution/IdeaInputHandler.java:17

// Copyright 2000-2024 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
package com.intellij.rt.ant.execution;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.input.InputHandler;
import org.apache.tools.ant.input.InputRequest;
import org.apache.tools.ant.input.MultipleChoiceInputRequest;

import java.io.IOException;
import java.util.List;

public class IdeaInputHandler implements InputHandler {
  @Override
  public void handleInput(InputRequest request) throws BuildException {
    final String prompt = request.getPrompt();
    if (prompt == null) {
      throw new BuildException("Prompt is null");
    }
    final SegmentedOutputStream err = IdeaAntLogger2.ourErr;
    if (err == null) {
      throw new BuildException("Selected InputHandler should be used by Intellij IDEA");
    }
    final PacketWriter packet = PacketFactory.ourInstance.createPacket(AntLoggerConstants.INPUT_REQUEST);
    packet.appendLimitedString(prompt);
    packet.appendLimitedString(request.getDefaultValue());
    if (request instanceof MultipleChoiceInputRequest) {
      @SuppressWarnings("unchecked") 
      List<String> choices = ((MultipleChoiceInputRequest)request).getChoices();
      if (choices != null && !choices.isEmpty()) {
        int count = choices.size();
        packet.appendLong(count);
        for (String choice : choices) {
          packet.appendLimitedString(choice);
        }
      }

View on GitHub (pinned to be881553f2)

Solutions

1. Fix the build/task so every <input> task has a non-empty prompt attribute (validtext/message).
2. If a custom task creates InputRequest programmatically, pass a non-null prompt string.
3. As a workaround, run the build with a different input handler (e.g. -inputhandler org.apache.tools.ant.input.DefaultInputHandler) to see where the null prompt originates.

Example fix

<!-- before -->
<input addproperty="v"/>
<!-- after -->
<input message="Enter value:" addproperty="v"/>

<input message="Enter value:" addproperty="v"/> <!-- always provide message/prompt -->

When it happens

Trigger: An Ant build executes an <input> task whose request was constructed without a prompt string (custom Ant version or a task creating InputRequest(null, ...)), and the build uses -inputhandler com.intellij.rt.ant.execution.IdeaInputHandler.

Common situations: Custom Ant tasks or macros that instantiate InputRequest directly with a null prompt; malformed third-party build files; running the same build under IDEA where the IDE-specific input handler is forced on.

Related errors

• \nThe version of the executed Ant is not compatible with the
• Selected InputHandler should be used by Intellij IDEA
• Invalid input: {input}
• Malformed exclusion, 'groupId:artifactName' format is expect
• Row %d failed: hierarchicalIdx cannot be null

AI-assisted analysis of JetBrains/intellij-community@be881553f2 (2026-08-14). Data as JSON: /api/errors/aff3aafdf084bc15. Report an issue: GitHub.