Unable to find artifact "copy-protoc:generate-sources" - eclipse

Question

I'm using Google's Protocol Buffers in a project. We use Maven to compile the protobufs automatically ( based on http://vlkan.com/blog/post/2015/11/27/maven-protobuf/ )
Maven gave us tree errors which we were able to solve by installing Maven Plugins on our Eclipse installation. But there is one error we can't solve :
org.apache.maven.plugins:maven-dependency-plugin:2.9:copy:copy-protoc:generate-sources
This error comes and goes apparently "randomly" and it doesn't break the compilation: everything works perfectly fine.
Here is the maven plugin configuration responsible for this problem:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.9</version>
<executions>
ERROR HERE - <execution>
<id>copy-protoc</id>
<phase>generate-sources</phase>
<goals>
<goal>copy</goal>
</goals>
<configuration>
<artifactItems>
<artifactItem>
<groupId>com.google.protobuf</groupId>
<artifactId>protoc</artifactId>
<version>3.0.0-beta-3</version>
<classifier>${os.detected.classifier}</classifier>
<type>exe</type>
<outputDirectory>${project.build.directory}</outputDirectory>
</artifactItem>
</artifactItems>
</configuration>
</execution>
</executions>
</plugin>
I tried deleting the .m2 folder or looking for more plugins to no avail.
How to remove that error from Eclipse? Thanks
Edit 1 , the whole stacktrace:
Unable to find artifact. (org.apache.maven.plugins:maven-dependency-plugin:2.9:copy:copy-protoc:generate-sources)
org.apache.maven.plugin.MojoExecutionException: Unable to find artifact.
at org.apache.maven.plugin.dependency.fromConfiguration.AbstractFromConfigurationMojo.getArtifact(AbstractFromConfigurationMojo.java:265)
at org.apache.maven.plugin.dependency.fromConfiguration.AbstractFromConfigurationMojo.getProcessedArtifactItems(AbstractFromConfigurationMojo.java:171)
at org.apache.maven.plugin.dependency.fromConfiguration.CopyMojo.doExecute(CopyMojo.java:105)
at org.apache.maven.plugin.dependency.AbstractDependencyMojo.execute(AbstractDependencyMojo.java:167)
at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:134)
at org.eclipse.m2e.core.internal.embedder.MavenImpl.execute(MavenImpl.java:331)
at org.eclipse.m2e.core.internal.embedder.MavenImpl$11.call(MavenImpl.java:1362)
at org.eclipse.m2e.core.internal.embedder.MavenImpl$11.call(MavenImpl.java:1)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.executeBare(MavenExecutionContext.java:176)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:112)
at org.eclipse.m2e.core.internal.embedder.MavenImpl.execute(MavenImpl.java:1360)
at org.eclipse.m2e.core.project.configurator.MojoExecutionBuildParticipant.build(MojoExecutionBuildParticipant.java:52)
at com.ianbrandt.tools.m2e.mdp.core.MdpBuildParticipant.executeMojo(MdpBuildParticipant.java:133)
at com.ianbrandt.tools.m2e.mdp.core.MdpBuildParticipant.build(MdpBuildParticipant.java:67)
at org.eclipse.m2e.core.internal.builder.MavenBuilderImpl.build(MavenBuilderImpl.java:137)
at org.eclipse.m2e.core.internal.builder.MavenBuilder$1.method(MavenBuilder.java:172)
at org.eclipse.m2e.core.internal.builder.MavenBuilder$1.method(MavenBuilder.java:1)
at org.eclipse.m2e.core.internal.builder.MavenBuilder$BuildMethod$1$1.call(MavenBuilder.java:115)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.executeBare(MavenExecutionContext.java:176)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:112)
at org.eclipse.m2e.core.internal.builder.MavenBuilder$BuildMethod$1.call(MavenBuilder.java:105)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.executeBare(MavenExecutionContext.java:176)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:151)
at org.eclipse.m2e.core.internal.embedder.MavenExecutionContext.execute(MavenExecutionContext.java:99)
at org.eclipse.m2e.core.internal.builder.MavenBuilder$BuildMethod.execute(MavenBuilder.java:86)
at org.eclipse.m2e.core.internal.builder.MavenBuilder.build(MavenBuilder.java:200)
at org.eclipse.core.internal.events.BuildManager$2.run(BuildManager.java:734)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:205)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:245)
at org.eclipse.core.internal.events.BuildManager$1.run(BuildManager.java:300)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:303)
at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:359)
at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:382)
at org.eclipse.core.internal.events.AutoBuildJob.doBuild(AutoBuildJob.java:144)
at org.eclipse.core.internal.events.AutoBuildJob.run(AutoBuildJob.java:235)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)
Caused by: org.apache.maven.artifact.resolver.ArtifactNotFoundException: Failure to find com.google.protobuf:protoc:exe:3.0.0-beta-3 in https://repo.maven.apache.org/maven2 was cached in the local repository, resolution will not be reattempted until the update interval of central has elapsed or updates are forced
Try downloading the file manually from the project website.
Then, install it using the command:
mvn install:install-file -DgroupId=com.google.protobuf -DartifactId=protoc -Dversion=3.0.0-beta-3 -Dpackaging=exe -Dfile=/path/to/file
Alternatively, if you host your own repository you can deploy the file there:
mvn deploy:deploy-file -DgroupId=com.google.protobuf -DartifactId=protoc -Dversion=3.0.0-beta-3 -Dpackaging=exe -Dfile=/path/to/file -Durl=[url] -DrepositoryId=[id]
com.google.protobuf:protoc:exe:3.0.0-beta-3
from the specified remote repositories:
central (https://repo.maven.apache.org/maven2, releases=true, snapshots=false)
at org.apache.maven.artifact.resolver.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:218)
at org.apache.maven.artifact.resolver.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:154)
at org.apache.maven.artifact.resolver.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:545)
at org.apache.maven.plugin.dependency.fromConfiguration.AbstractFromConfigurationMojo.getArtifact(AbstractFromConfigurationMojo.java:257)
... 37 more
Caused by: org.eclipse.aether.resolution.ArtifactResolutionException: Failure to find com.google.protobuf:protoc:exe:3.0.0-beta-3 in https://repo.maven.apache.org/maven2 was cached in the local repository, resolution will not be reattempted until the update interval of central has elapsed or updates are forced
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:444)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolveArtifacts(DefaultArtifactResolver.java:246)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolveArtifact(DefaultArtifactResolver.java:223)
at org.eclipse.aether.internal.impl.DefaultRepositorySystem.resolveArtifact(DefaultRepositorySystem.java:294)
at org.apache.maven.artifact.resolver.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:212)
... 40 more
Caused by: org.eclipse.aether.transfer.ArtifactNotFoundException: Failure to find com.google.protobuf:protoc:exe:3.0.0-beta-3 in https://repo.maven.apache.org/maven2 was cached in the local repository, resolution will not be reattempted until the update interval of central has elapsed or updates are forced
at org.eclipse.aether.internal.impl.DefaultUpdateCheckManager.newException(DefaultUpdateCheckManager.java:231)
at org.eclipse.aether.internal.impl.DefaultUpdateCheckManager.checkArtifact(DefaultUpdateCheckManager.java:206)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.gatherDownloads(DefaultArtifactResolver.java:585)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.performDownloads(DefaultArtifactResolver.java:503)
at org.eclipse.aether.internal.impl.DefaultArtifactResolver.resolve(DefaultArtifactResolver.java:421)
... 44 more
Edit 2 , The Effective POM:
Effective POMs, after inheritance, interpolation, and profiles are applied:
<!-- ====================================================================== -->
<!-- -->
<!-- Generated by Maven Help Plugin on 2016-06-01T01:19:06 -->
<!-- See: http://maven.apache.org/plugins/maven-help-plugin/ -->
<!-- -->
<!-- ====================================================================== -->
<!-- ====================================================================== -->
<!-- -->
<!-- Effective POM for project 'com.GroupName:ProjectName:jar:1.0-SNAPSHOT' -->
<!-- -->
<!-- ====================================================================== -->
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.GroupName</groupId>
<artifactId>ProjectName</artifactId>
<version>1.0-SNAPSHOT</version>
<name>ProjectName</name>
<url>http://maven.apache.org</url>
<properties>
<build-helper-maven-plugin.version>1.9.1</build-helper-maven-plugin.version>
<java.version>1.8</java.version>
<junit.version>4.12</junit.version>
<maven-antrun-plugin.version>1.8</maven-antrun-plugin.version>
<maven-dependency-plugin.version>2.9</maven-dependency-plugin.version>
<maven-shade-plugin.version>2.4.3</maven-shade-plugin.version>
<os-maven-plugin.version>1.5.0.Final</os-maven-plugin.version>
<os.detected.arch>x86_64</os.detected.arch>
<os.detected.classifier>windows-x86_64</os.detected.classifier>
<os.detected.name>windows</os.detected.name>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<protobuf-java-format.version>1.2</protobuf-java-format.version>
<protobuf.input.directory>E:\Development\GroupName\ProjectFolder/proto</protobuf.input.directory>
<protobuf.output.directory.cpp>E:\Development\GroupName\ProjectFolder\target/libcpp</protobuf.output.directory.cpp>
<protobuf.output.directory.java>E:\Development\GroupName\ProjectFolder\target/generated-sources</protobuf.output.directory.java>
<protobuf.version>3.0.0-beta-3</protobuf.version>
</properties>
<dependencies>
<dependency>
<groupId>com.google.protobuf</groupId>
<artifactId>protobuf-java</artifactId>
<version>3.0.0-beta-3</version>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>com.googlecode.protobuf-java-format</groupId>
<artifactId>protobuf-java-format</artifactId>
<version>1.2</version>
<scope>compile</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
</dependencies>
<repositories>
<repository>
<snapshots>
<enabled>false</enabled>
</snapshots>
<id>central</id>
<name>Central Repository</name>
<url>https://repo.maven.apache.org/maven2</url>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<releases>
<updatePolicy>never</updatePolicy>
</releases>
<snapshots>
<enabled>false</enabled>
</snapshots>
<id>central</id>
<name>Central Repository</name>
<url>https://repo.maven.apache.org/maven2</url>
</pluginRepository>
</pluginRepositories>
<build>
<sourceDirectory>E:\Development\GroupName\ProjectFolder\src\main\java</sourceDirectory>
<scriptSourceDirectory>E:\Development\GroupName\ProjectFolder\src\main\scripts</scriptSourceDirectory>
<testSourceDirectory>E:\Development\GroupName\ProjectFolder\src\test\java</testSourceDirectory>
<outputDirectory>E:\Development\GroupName\ProjectFolder\target\classes</outputDirectory>
<testOutputDirectory>E:\Development\GroupName\ProjectFolder\target\test-classes</testOutputDirectory>
<extensions>
<extension>
<groupId>kr.motd.maven</groupId>
<artifactId>os-maven-plugin</artifactId>
<version>1.5.0.Final</version>
</extension>
</extensions>
<resources>
<resource>
<directory>E:\Development\GroupName\ProjectFolder\src\main\resources</directory>
</resource>
</resources>
<testResources>
<testResource>
<directory>E:\Development\GroupName\ProjectFolder\src\test\resources</directory>
</testResource>
</testResources>
<directory>E:\Development\GroupName\ProjectFolder\target</directory>
<finalName>ProjectName</finalName>
<pluginManagement>
<plugins>
<plugin>
<artifactId>maven-antrun-plugin</artifactId>
<version>1.3</version>
</plugin>
<plugin>
<artifactId>maven-assembly-plugin</artifactId>
<version>2.2-beta-5</version>
</plugin>
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.8</version>
</plugin>
<plugin>
<artifactId>maven-release-plugin</artifactId>
<version>2.3.2</version>
</plugin>
<plugin>
<groupId>org.eclipse.m2e</groupId>
<artifactId>lifecycle-mapping</artifactId>
<version>1.0.0</version>
<configuration>
<lifecycleMappingMetadata>
<pluginExecutions>
<pluginExecution>
<pluginExecutionFilter>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-antrun-plugin</artifactId>
<versionRange>[1.7,)</versionRange>
<goals>
<goal>run</goal>
</goals>
</pluginExecutionFilter>
<action>
<ignore />
<execute>
<runOnConfiguration>true</runOnConfiguration>
<runOnIncremental>true</runOnIncremental>
</execute>
</action>
</pluginExecution>
</pluginExecutions>
</lifecycleMappingMetadata>
</configuration>
</plugin>
</plugins>
</pluginManagement>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.3</version>
<executions>
<execution>
<id>default-compile</id>
<phase>compile</phase>
<goals>
<goal>compile</goal>
</goals>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</execution>
<execution>
<id>default-testCompile</id>
<phase>test-compile</phase>
<goals>
<goal>testCompile</goal>
</goals>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</execution>
</executions>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
<plugin>
<artifactId>maven-resources-plugin</artifactId>
<version>2.7</version>
<executions>
<execution>
<id>default-testResources</id>
<phase>process-test-resources</phase>
<goals>
<goal>testResources</goal>
</goals>
<configuration>
<encoding>UTF-8</encoding>
</configuration>
</execution>
<execution>
<id>default-resources</id>
<phase>process-resources</phase>
<goals>
<goal>resources</goal>
</goals>
<configuration>
<encoding>UTF-8</encoding>
</configuration>
</execution>
</executions>
<configuration>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
<plugin>
<artifactId>maven-dependency-plugin</artifactId>
<version>2.9</version>
<executions>
<execution>
<id>copy-protoc</id>
<phase>generate-sources</phase>
<goals>
<goal>copy</goal>
</goals>
<configuration>
<artifactItems>
<artifactItem>
<groupId>com.google.protobuf</groupId>
<artifactId>protoc</artifactId>
<version>3.0.0-beta-3</version>
<classifier>${os.detected.classifier}</classifier>
<type>exe</type>
<outputDirectory>E:\Development\GroupName\ProjectFolder\target</outputDirectory>
</artifactItem>
</artifactItems>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-antrun-plugin</artifactId>
<version>1.8</version>
<executions>
<execution>
<id>exec-protoc</id>
<phase>generate-sources</phase>
<goals>
<goal>run</goal>
</goals>
<configuration>
<target>
<property name="protoc.filename" value="protoc-3.0.0-beta-3-${os.detected.classifier}.exe" />
<property name="protoc.filepath" value="E:\Development\GroupName\ProjectFolder\target/${protoc.filename}" />
<chmod file="${protoc.filepath}" perm="ugo+rx" />
<mkdir dir="E:\Development\GroupName\ProjectFolder\target/generated-sources" />
<mkdir dir="E:\Development\GroupName\ProjectFolder\target/libcpp" />
<path id="protobuf.input.filepaths.path">
<fileset dir="E:\Development\GroupName\ProjectFolder/proto">
<include name="**/*.proto" />
</fileset>
</path>
<pathconvert property="protobuf.input.filepaths" pathsep=" " refid="protobuf.input.filepaths.path" />
<exec failonerror="true" executable="${protoc.filepath}">
<arg value="-I" />
<arg value="E:\Development\GroupName\ProjectFolder/proto" />
<arg value="--java_out" />
<arg value="E:\Development\GroupName\ProjectFolder\target/generated-sources" />
<arg value="--cpp_out" />
<arg value="E:\Development\GroupName\ProjectFolder\target/libcpp" />
<arg line="${protobuf.input.filepaths}" />
</exec>
</target>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.codehaus.mojo</groupId>
<artifactId>build-helper-maven-plugin</artifactId>
<version>1.9.1</version>
<executions>
<execution>
<id>add-classes</id>
<phase>generate-sources</phase>
<goals>
<goal>add-source</goal>
</goals>
<configuration>
<sources>
<source>E:\Development\GroupName\ProjectFolder\target/generated-sources</source>
</sources>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-clean-plugin</artifactId>
<version>2.5</version>
<executions>
<execution>
<id>default-clean</id>
<phase>clean</phase>
<goals>
<goal>clean</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-jar-plugin</artifactId>
<version>2.4</version>
<executions>
<execution>
<id>default-jar</id>
<phase>package</phase>
<goals>
<goal>jar</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.12.4</version>
<executions>
<execution>
<id>default-test</id>
<phase>test</phase>
<goals>
<goal>test</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-install-plugin</artifactId>
<version>2.4</version>
<executions>
<execution>
<id>default-install</id>
<phase>install</phase>
<goals>
<goal>install</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-deploy-plugin</artifactId>
<version>2.7</version>
<executions>
<execution>
<id>default-deploy</id>
<phase>deploy</phase>
<goals>
<goal>deploy</goal>
</goals>
</execution>
</executions>
</plugin>
<plugin>
<artifactId>maven-site-plugin</artifactId>
<version>3.3</version>
<executions>
<execution>
<id>default-site</id>
<phase>site</phase>
<goals>
<goal>site</goal>
</goals>
<configuration>
<outputDirectory>E:\Development\GroupName\ProjectFolder\target\site</outputDirectory>
<reportPlugins>
<reportPlugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-project-info-reports-plugin</artifactId>
</reportPlugin>
</reportPlugins>
</configuration>
</execution>
<execution>
<id>default-deploy</id>
<phase>site-deploy</phase>
<goals>
<goal>deploy</goal>
</goals>
<configuration>
<outputDirectory>E:\Development\GroupName\ProjectFolder\target\site</outputDirectory>
<reportPlugins>
<reportPlugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-project-info-reports-plugin</artifactId>
</reportPlugin>
</reportPlugins>
</configuration>
</execution>
</executions>
<configuration>
<outputDirectory>E:\Development\GroupName\ProjectFolder\target\site</outputDirectory>
<reportPlugins>
<reportPlugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-project-info-reports-plugin</artifactId>
</reportPlugin>
</reportPlugins>
</configuration>
</plugin>
</plugins>
</build>
<reporting>
<outputDirectory>E:\Development\GroupName\ProjectFolder\target\site</outputDirectory>
</reporting>
</project>

Answer 1

Thanks for posting this question. I was facing a similar issues in my pom.
It got resolved once I changed maven dependency plugin version to 3.0.0
Another thing that I wasn't sure about was the maven-dependency plugin's os detected classifier, so I gave it manually. I see that you have also defined it manually so updating the dependency plugin itself should resolve this issue.