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Maven error in OS X: “Maven already installed, it’s just not linked”

If you use Homebrew on OS X and you come across the error below, just:

  1. $ rm -rf /usr/local/Cellar/maven
  2. $ brew install maven
  3. $ mvn -version
  4. That’s it!

$ brew install maven
Updating Homebrew...
==> Auto-updated Homebrew!
Updated 2 taps (caskroom/cask, caskroom/versions).

Warning: maven-3.5.0 already installed, it's just not linked.

Maven build error: “Caused by: java.io.IOException: Incompatible version 1007”

I was encountering this error in Jenkins when it tried to build a project I was working on:


Caused by: java.io.IOException: Incompatible version 1007.
at org.jacoco.core.data.ExecutionDataReader.readHeader(ExecutionDataReader.java:127)
at org.jacoco.core.data.ExecutionDataReader.readBlock(ExecutionDataReader.java:107)
at org.jacoco.core.data.ExecutionDataReader.read(ExecutionDataReader.java:87)
at org.sonar.plugins.jacoco.AbstractAnalyzer.readExecutionData(AbstractAnalyzer.java:134)
at org.sonar.plugins.jacoco.AbstractAnalyzer.analyse(AbstractAnalyzer.java:107)

The problem was due to a breakage/bug in the jacoco-maven-plugin. To fix, simply add a version in your pom.xml, like so:


<plugin>
    <groupId>org.jacoco</groupId>
    <artifactId>jacoco-maven-plugin</artifactId>
    <version>0.7.4.201502262128</version>
    <executions>
        <execution>
            <goals>
                <goal>prepare-agent</goal>
            </goals>
        </execution>
    </executions>
</plugin>

That’s it!