IntelliJ IDEA 2017.2 Help

Troubleshooting common Maven issues

If you encounter problems working with your Maven project you can check to see if the following solutions and workarounds can help you solve your issues.

How to fix compiler version problems in Maven projects

In some cases when you import a Maven project, it might have compiler settings that will not match the expected settings in IntelliJ IDEA and when you compile your code, you might encounter a problem.

For example, you can get the following error:

maven error sample

This error usually indicates a problem with the compiler version compatibility and you can check few places to fix it.

  • You can edit your POM and configure Maven compiler plugin to compile your Java code. You should set the compiler level explicitly, so it won't revert to the default settings when you re-import your project.
    1. Open your POM in the editor.
    2. Change the configuration for the Maven compiler plugin.
      maven compiler plugin
      Click the reimport icon icon to import your changes. Also note the configurations specified in your POM overrides any configurations specified in your project structure. So, now after this project is imported the language level should be be picked up.
  • Check Java compiler settings to see if bytecode versions match.
    1. On the main menu, select File | Settings.
    2. In the Settings dialog, select Build, Execution, Deployment | Compiler | Java Compiler from options on the left.
    3. On the page that opens, check if Project bytecode version and Target bytecode version match, or leave the Target bytecode version option blank so it can be determined from JDK.
      maven check bytecode version
  • If you have imported a multi-level project, you can check project structure settings for source language level configuration.
    1. Open Project Structure dialog and select Project from the options on the left.
    2. Check the source language level for your project.
      maven project level
    3. Check the source language level for each module (click the Sources tab).
      maven module level

How to fix problems with Maven projects that won't start

To fix issues that are related to the Maven projects that won't start or import, check the following:

  • If you received the OutOfMemory error, try to increase heap size for the Maven importer.
    1. Open Settings dialog (click the settings icon in the Maven Projects tool window).
    2. Select Maven | Importing from option on the left.
    3. On the Importing page, in the VM options for importer field, increase heap size for the Maven importer.
      maven vm for importer options
    4. Also, in the JDK for importer field, increase IDE heap size.
      maven jdk for importer
      (Try not to exceed 750-1024m for -Xmx value if you are running on a 32-bit JVM (default), otherwise it may crash or fail to start.) If you need to use more heap, switch to 64-bit Java and specify the same 64-bit JVM for Maven JDK for importer.
  • If you received the Operation timed out error or IDE connection failure to the Maven process, try to edit the hosts file.
    • On some systems you need to edit the hosts file so that localhost resolves correctly. Try to have localhost in the etc/hosts file. Also make sure there are no other IP addresses mapped to localhost.
  • If the error indicates the Maven repository issue, such as the Failed to update Maven indices error, try to check if Maven repositories were indexed correctly.

    IntelliJ IDEA works with repository indexes. The indexes are fetched remotely from remote repositories. Some repositories do not provide indexes, or do not keep an updated index, for example, repositories from Bintray, in this case you can ignore the error.

    If you have an indexed repository, but still get a Maven repository error, check the following options:

    1. Open the Maven Settings dialog (click the settings icon in the Maven Projects tool window).
    2. On the Maven page, in the User settings file field, check if you defined proper credentials for the server in settings.xml.
      maven user setting file

    You can try to restart IntelliJ IDEA and update Maven repositories.

    1. Open the Maven Settings dialog (click the settings icon in the Maven Projects tool window).
    2. Select Repositories from options on the left.
    3. On the Repositories page, Update Maven repositories.
      maven repos
Last modified: 29 November 2017