Maven父项目执行mvn site报错：参数'from'不能为空

在Maven父项目中执行mvn site命令时，其中一个子项目构建失败，核心报错信息如下：

maven-site-plugin:3.10.0:site failed: The parameter 'from' cannot be null. -> [Help 1]

完整报错堆栈：

org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal org.apache.maven.plugins:maven-site-plugin:3.10.0:site (default-site) on project eleusoft_links_support: Execution default-site of goal org.apache.maven.plugins:maven-site-plugin:3.10.0:site failed: The parameter 'from' cannot be null.
at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2 (MojoExecutor.java:375)
at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute (MojoExecutor.java:351)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:215)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:171)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:163)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:299)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:193)
at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:106)
at org.apache.maven.cli.MavenCli.execute (MavenCli.java:963)
at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:296)
at org.apache.maven.cli.MavenCli.main (MavenCli.java:199)
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke (Method.java:498)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
Caused by: org.apache.maven.plugin.PluginExecutionException: Execution default-site of goal org.apache.maven.plugins:maven-site-plugin:3.10.0:site failed: The parameter 'from' cannot be null.
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:148)
at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2 (MojoExecutor.java:370)
at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute (MojoExecutor.java:351)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:215)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:171)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:163)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:299)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:193)
at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:106)
at org.apache.maven.cli.MavenCli.execute (MavenCli.java:963)
at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:296)
at org.apache.maven.cli.MavenCli.main (MavenCli.java:199)
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke (Method.java:498)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)
Caused by: java.lang.IllegalArgumentException: The parameter 'from' cannot be null.
at org.apache.maven.doxia.tools.DefaultSiteTool.checkNotNull (DefaultSiteTool.java:1493)
at org.apache.maven.doxia.tools.DefaultSiteTool.getRelativePath (DefaultSiteTool.java:192)
at org.apache.maven.doxia.tools.DefaultSiteTool.populateParentMenu (DefaultSiteTool.java:711)
at org.apache.maven.doxia.tools.DefaultSiteTool.getDecorationModel (DefaultSiteTool.java:494)
at org.apache.maven.plugins.site.descriptor.AbstractSiteDescriptorMojo.prepareDecorationModel (AbstractSiteDescriptorMojo.java:86)
at org.apache.maven.plugins.site.render.AbstractSiteRenderingMojo.createSiteRenderingContext (AbstractSiteRenderingMojo.java:275)
at org.apache.maven.plugins.site.render.SiteMojo.renderLocale (SiteMojo.java:164)
at org.apache.maven.plugins.site.render.SiteMojo.execute (SiteMojo.java:143)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo (DefaultBuildPluginManager.java:137)
at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute2 (MojoExecutor.java:370)
at org.apache.maven.lifecycle.internal.MojoExecutor.doExecute (MojoExecutor.java:351)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:215)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:171)
at org.apache.maven.lifecycle.internal.MojoExecutor.execute (MojoExecutor.java:163)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:117)
at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject (LifecycleModuleBuilder.java:81)
at org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build (SingleThreadedBuilder.java:56)
at org.apache.maven.lifecycle.internal.LifecycleStarter.execute (LifecycleStarter.java:128)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:299)
at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:193)
at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:106)
at org.apache.maven.cli.MavenCli.execute (MavenCli.java:963)
at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:296)
at org.apache.maven.cli.MavenCli.main (MavenCli.java:199)
at sun.reflect.NativeMethodAccessorImpl.invoke0 (Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke (NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke (DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke (Method.java:498)
at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced (Launcher.java:282)
at org.codehaus.plexus.classworlds.launcher.Launcher.launch (Launcher.java:225)
at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode (Launcher.java:406)
at org.codehaus.plexus.classworlds.launcher.Launcher.main (Launcher.java:347)

问题原因 #

从报错堆栈可追踪到根因：生成站点导航菜单时，插件需要计算子项目站点到父项目站点的相对路径，但此时子项目的站点输出目录（即报错中的from参数）为空，触发了空参数校验异常。

常见触发场景：

• 子项目未配置maven-site-plugin的输出目录，继承父项目配置后未正确初始化路径；
• 子项目是纯业务模块（如jar包），不需要生成站点，但父项目执行site命令时强制触发了该子项目的site构建目标。

修复方案 #

方案1：给子项目指定site输出目录 #

在报错子项目的pom.xml中添加或完善插件配置，明确输出路径：

<build>
  <plugins>
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-site-plugin</artifactId>
      <version>3.10.0</version>
      <configuration>
        <outputDirectory>${project.build.directory}/site</outputDirectory>
      </configuration>
    </plugin>
  </plugins>
</build>

方案2：父项目跳过该子项目的site构建 #

如果子项目不需要生成站点，在父项目的pom.xml中配置插件时，排除这个子项目：

<build>
  <plugins>
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-site-plugin</artifactId>
      <version>3.10.0</version>
      <executions>
        <execution>
          <id>default-site</id>
          <goals>
            <goal>site</goal>
          </goals>
          <configuration>
            <projects>!eleusoft_links_support</projects>
          </configuration>
        </execution>
      </executions>
    </plugin>
  </plugins>
</build>

方案3：升级插件版本 #

该问题可能是旧版本插件的bug，尝试升级到最新稳定版（如3.12.0），新版本可能修复了空参数的校验逻辑：

<build>
  <plugins>
    <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-site-plugin</artifactId>
      <version>3.12.0</version>
    </plugin>
  </plugins>
</build>

内容的提问来源于stack exchange，提问作者Testo Testini