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Can't execute jar- file: "no main manifest attribute"

I have installed an application, when I try to run it (it's an executable jar) nothing happens. When I run it from the commandline with:

java -jar "app.jar"

I get the following message:

no main manifest attribute, in "app.jar"

Normally, if I had created the program myself, I would have added a main class attribute to the manifest file. But in this case, since the file is from an application, i cannot do that. I also tried extracting the jar to see if I could find the main class, but there are to many classes and none of them has the word "main" in it's name. There must be a way to fix this because the program runs fine on other systems.

Look for main methods; you can't rely on class names.
I know, but since I only have .class files I can't really see the methods. Or can I?
You aren't really typing the quotes, are you? In any case, there are a number of ways to see methods, include using javap. You might want to un-jar it and look to see if there's actually no manifest, though.
Related: with dependencies: stackoverflow.com/a/23986765/360211
what if I don't have main class as I am running the code using CommandLineJobRunner

K
Kobedi

First, it's kind of weird, to see you run java -jar "app" and not java -jar app.jar

Second, to make a jar executable... you need to jar a file called META-INF/MANIFEST.MF

the file itself should have (at least) this one liner:

Main-Class: com.mypackage.MyClass

Where com.mypackage.MyClass is the class holding the public static void main(String[] args) entry point.

Note that there are several ways to get this done either with the CLI, Maven, Ant or Gradle:

For CLI, the following command will do: (tks @dvvrt)

jar cmvf META-INF/MANIFEST.MF <new-jar-filename>.jar  <files to include>

For Maven, something like the following snippet should do the trick. Note that this is only the plugin definition, not the full pom.xml:

Latest doc on this plugin: see https://maven.apache.org/plugins/maven-jar-plugin/

<build>
  <plugins>
    <plugin>
      <!-- Build an executable JAR -->
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-jar-plugin</artifactId>
      <version>3.1.0</version>
      <configuration>
        <archive>
          <manifest>
            <addClasspath>true</addClasspath>
            <classpathPrefix>lib/</classpathPrefix>
            <mainClass>com.mypackage.MyClass</mainClass>
          </manifest>
        </archive>
      </configuration>
    </plugin>
  </plugins>
</build>

(Pick a <version> appropriate to your project.)

For Ant, the snippet below should help:

<jar destfile="build/main/checksites.jar">
  <fileset dir="build/main/classes"/>
  <zipfileset includes="**/*.class" src="lib/main/some.jar"/>
  <manifest>
    <attribute name="Main-Class" value="com.acme.checksites.Main"/>
  </manifest>
</jar>

Credits Michael Niemand -

For Gradle:

plugins {
    id 'java'
}

jar {
    manifest {
        attributes(
                'Main-Class': 'com.mypackage.MyClass'
        )
    }
}

In Ant its within the element
Thank you. Just wanted to add that you can copy dependencies to the lib folder using this: stackoverflow.com/a/996915/1121497. Since the classpath includes that lib folder then you only need to execute the jar with java -jar myproject.jar and it will find the dependencies.
HOW TO "jar a file called META-INF/MANIFEST.MF" ? I have a .jar on one hand and a .MF on the other, how do I link them together ? I put the manifest in the same folder as the .jar but it doesn't work I still got the problem !
@Wicelo To specify a specific MANIFEST.MF file while creating a jar file use the m flag for jar. eg. jar cmvf META-INF/MANIFEST.MF <new-jar-filename>.jar <files to include>
Note: For Maven, I already had a maven-jar-plugin item in the VSC-generated Maven file, so I just added the <configuration> section to it.
J
Jesper

That should have been java -jar app.jar instead of java -jar "app".

The -jar option only works if the JAR file is an executable JAR file, which means it must have a manifest file with a Main-Class attribute in it. See Packaging Programs in JAR Files to learn how to create an executable JAR.

If it's not an executable JAR, then you'll need to run the program with something like:

java -cp app.jar com.somepackage.SomeClass

where com.somepackage.SomeClass is the class that contains the main method to run the program. (What that class is depends on the program, it's impossible to tell from the information you've supplied).


thanks for your reply, but your solution only works if I know the name of the class that contains the main method. And it was a typo... It was supposed to be "app.jar". But how do you explain why it runs on other systems by just double clicking the file?
If it is indeed an executable JAR, you can extract the manifest file (it's in the META-INF directory inside the JAR file). It should contain a Main-Class attribute that gives you the name of the main class.
If it doesn run on one system, then that system maybe has a too old Java version. If the JAR is for example compiled with Java 7, then you can't run it on a system that has Java 6 or older.
That's funny since the other system is running win7 and this pc with the problems runs win8.
@Jesper Hello, what if eclipse is using the default package? Do I just put the class name?
e
eis

Alternatively, you can use maven-assembly-plugin, as shown in the below example:

<plugin>
    <artifactId>maven-assembly-plugin</artifactId>
    <executions>
      <execution>
        <phase>package</phase>
        <goals>
          <goal>single</goal>
        </goals>
      </execution>
    </executions>
    <configuration>
      <archive>
        <manifest>
          <addClasspath>true</addClasspath>
          <mainClass>com.package.MainClass</mainClass>
        </manifest>
      </archive>
      <descriptorRefs>
        <descriptorRef>jar-with-dependencies</descriptorRef>
      </descriptorRefs>
    </configuration>
  </plugin> 

In this example all the dependency jars as specified in section will be automatically included in your single jar. Note that jar-with-dependencies should be literally put as, not to be replaced with the jar file names you want to include.


Perfect, this works. It bundles all dependencies in to one jar, thus allowing you to compile/build a project and run it out of the box.
In the context of the shade plugin, one has to follow the help at Executable JAR.
This with maven-assembly-plugin worked. maven-jar-plugin did not.
Note: put this code in your pom.xml file inside <build><plugins> PUT IT HERE </plugins></build> and then execute maven Package (in IDEA open maven sliding menu on the right, look for project > Lifecycle > package). Then your jar file will be in Target folder . Cheers!
I was really struggling with this issue...This works perfectly. Thanks!
S
Sasanka Panguluri

That is because Java cannot find the Main attribute in the MANIFEST.MF file. The Main attribute is necessary to tell java which class it should use as the application's entry point. Inside the jar file, the MANIFEST.MF file is located in META-INF folder. Wondering how you could look at what's inside a jar file? Open the jar file with WinRAR.

The main attribute inside the MANIFEST.MF looks like this:

Main-Class: <packagename>.<classname>

You get this "no main manifest attribute" error when this line is missing from the MANIFEST.MF file.

It's really a huge mess to specify this attribute inside the MANIFEST.MF file.

Update: I just found a really neat way to specify the Application's entry point in eclipse. When you say Export,

Select Jar and next 

[ give it a name in the next window ] and next

and next again

and you'll see " Select the class of the application entry point".

Just pick a class and Eclipse will automatically build a cool MANIFEST.MF for you.

https://i.stack.imgur.com/9V7F3.png


N
Naga Srinu Kapusetti

I had the same issue. by adding following lines to pom file made it work. The plugin will make sure the build process of your application with all necessary steps.

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

worked perfectly, but consider adding the version as of April 2018 org.springframework.boot spring-boot-maven-plugin 2.0.1.RELEASE
Sorry but it's not a solution because he is not talking about Spring Boot, it's general problem with jar execution :)
Thanks a lot, this solved the problem for spring boot!
I am working on spring boot 2.2.0.Release. Unfortunately, this solution did not work for me. However, it works when you have referred from a <parent>...</parent> application in the pom.xml. My guess is, if we visit the parent application's pom.xml, we will get a clear idea.
I finally solved my issue with the custom repackage-classifier. Please visit docs.spring.io/spring-boot/docs/2.2.0.RELEASE/maven-plugin/…
m
morningstar

I had this issue when creating a jar using IntelliJ IDEA. See this discussion.

What solved it for me was to re-create the jar artifact, choosing JAR > From modules with dependencies, but not accepting the default Directory for META-INF/MANIFEST.MF. Change it from -/src/main/java to -/src/main/resources.

Otherwise it was including a manifest file in the jar, but not the one in -/src/main/java that it should have.


This worked for me with IDEA 14.1.6. I also added the build property for pom.xml but it had no effect. But your answer solved it, thank you.
Thanks for saving my desktop from getting dented by the pure frustration of nothing else working ;) Your link seems broken, but I can confirm that this works perfectly. Tested with IntelliJ IDEA 2018.2.5 (Community Edition)
confirmed that this works, even though i dont have a /resources directory
broken link, did you mean https://stackoverflow.com/questions/20952713/wrong-manifest-mf-in-intellij-idea-created-jar?
Q
QED

The Gradle answer is to add a jar/manifest/attributes setting like this:

apply plugin: 'java'

jar {
    manifest {
        attributes 'Main-Class': 'com.package.app.Class'
    }
}

the simplest answer thus far.
For the Gradle build script written on Kotlin see this answer.
D
David

For maven, this is what solved it (for me, for a Veetle codebase on GitHub):

<build>
<plugins>
  <plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-shade-plugin</artifactId>
    <version>2.0</version>
    <executions>
      <execution>
        <phase>package</phase>
        <goals>
          <goal>shade</goal>
        </goals>
        <configuration>
          <transformers>
            <transformer implementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer">
              <mainClass>org.lazydevs.veetle.api.VeetleAPI</mainClass>
            </transformer>
          </transformers>
        </configuration>
      </execution>
    </executions>
  </plugin>
 </plugins>
</build>

Cheers...


I found this worked but I had to execute as mvn package shade:shade just running mvn package didn't trigger the shade plugin to run.
E
Eric Leschinski

Try this command to include the jar:

java -cp yourJarName.jar your.package..your.MainClass

One way is to include main class in pom.xml and use java -jar command, other one is to use java -cp command.
e
eis

For me, none of the answers really helped - I had the manifest file in correct place, containing the Main-Class and everything. What tripped me over was this:

Warning: The text file from which you are creating the manifest must end with a new line or carriage return. The last line will not be parsed properly if it does not end with a new line or carriage return.

(source). Adding a newline at the end of the manifest fixed it.


s
shuang

If using Maven, include following in the pom

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.4.2.RELEASE</version>
</parent>

<properties>
    <java.version>1.8</java.version>
</properties>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

Who said this was a Spring Boot project?
@james.garriss well I would say, I came to this post searching for no main manifest attribute error but I am working on spring boot application so this answer helped me. I already knew how to create META-INF/MANIFEST.MF file, but not how to make spring-boot automatically handles it.
I don't see any reason for downvoting this answer. If you are not using spring-boot just ignore it. Stackoverflow also helps to build your own issue repository which you face while programming.
@Vishrant I don't know about others but I downvoted because this answer does not address the question as it was posed. It may have just happened to answer your question, but your question wasn't really what was asked.
@Bane sure. but the question can be taken in a broad sense and this answer applies to it and can help others in the sense when they will use spring boot.
Y
Yury Finchenko

The MAVEN problem is that its try to include the first MANIFEST.MF file from first library from dependencies instead of THE OUR OWN MANIFEST.MF WHEN YOU USE ARTIFACTS!.

Rename yourjar.jar to yourjar.zip Open MANIFEST.MF file from META-INF\MANIFEST.MF Copy the real MANIFEST.MF that already generate in your project by MAVEN That include somelike that: Manifest-Version: 1.0 Main-Class: yourpacket.yourmainclass (for exmaple info.data.MainClass) Replace the content of MANIFEST.MF from youjar.zip with it. Rename yourjar.zip to yourjar.jar back. Now java -jar yourjar.jar work perfectly.

OR!

Simple create you own MANIFEST.MF and:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-jar-plugin</artifactId>
    <version>3.2.0</version>
    <configuration>
        <archive>
            <manifestFile> Your path like: src/main/resources/META-INF/MANIFEST.MF </manifestFile>
            <index>true</index>
                <manifest>
                    <addClasspath>true</addClasspath>
                </manifest>
        </archive>
    </configuration>
</plugin>

But if you use maven panel (or maven command line) you can force it to generate own manifest and include it into JAR file.

Add to the you pom.xml's build section this code: org.apache.maven.plugins maven-assembly-plugin 3.2.0 package single jar-with-dependencies true true yourpacket.yourmainclass (for exmaple info.data.MainClass) development ${project.url} Open the MAVEN panel (in Intellij) and execute "Install". It will generate the MANIFEST file and compile property the JAR file with all dependencies into the "Target" folder. Also it will be installed to the local maven repository.


M
MTA

I had the same issue today. My problem was solved my moving META-INF to the resources folder.


This worked for me too. Try it if you are using Jetbrains IntelliJ
B
Binakot

I got same error just now. If u're using gradle, just add next one in ur gradle.build:

apply plugin: 'java'

jar {
    manifest {
        attributes 'Main-Class': 'com.company.project.MainClass'
    }
}

Where com.company.project.MainClass path to ur class with public static void main(String[] args) method.


This helped me! gradle tutorials had specified using the top-level mainClassName variable set, but that only helps with gradle run command, not with creating an executable .jar
J
John M

If the jar isn't following the rules, it's not an executable jar.


+1 for the Jar File Specification link (docs.oracle.com/javase/1.4.2/docs/guide/jar/jar.html)
please be specific when you answer questions, see other answers
A
Andrew

If you are using the command line to assemble .jar it is possible to point to the main without adding Manifest file. Example:

jar cfve app.jar TheNameOfClassWithMainMethod *.class

(param "e" does that: TheNameOfClassWithMainMethod is a name of the class with the method main() and app.jar - name of executable .jar and *.class - just all classes files to assemble)


C
CodeMonkey

I had the same problem. A lot of the solutions mentioned here didn't give me the whole picture, so I'll try to give you a summary of how to pack jar files from the command line.

If you want to have your .class files in packages, add the package in the beginning of the .java. Test.java package testpackage; public class Test { ... } To compile your code with your .class files ending up with the structure given by the package name use: javac -d . Test.java The -d . makes the compiler create the directory structure you want. When packaging the .jar file, you need to instruct the jar routine on how to pack it. Here we use the option set cvfeP. This is to keep the package structure (option P), specify the entry point so that the manifest file contains meaningful information (option e). Option f lets you specify the file name, option c creates an archive and option v sets the output to verbose. The important things to note here are P and e. Then comes the name of the jar we want test.jar. Then comes the entry point . And then comes -C . / to get the class files from that folder, preserving the folder structure. jar cvfeP test.jar testpackage.Test -C . testpackage/ Check your .jar file in a zip program. It should have the following structure test.jar META-INF | MANIFEST.MF testpackage | Test.class The MANIFEST.MF should contain the following Manifest-Version: 1.0 Created-By: (Oracle Corporation) Main-Class: testpackage.Test If you edit your manifest by hand be sure to keep the newline at the end otherwise java doesn't recognize it. Execute your .jar file with java -jar test.jar


The 4th step of your answer is very important ! My manifest wasn't working because of that newline at the end I did not know I had to put. All answers I visited on this topic (a lot) did not mention this, and it is mandatory for anyone not using maven,ant,gradle, and so on.
@Maude thank you for the feedback. That's precisely why I added the answer with the newline hint in bold. I looked for days until I found this out by comparing with an auto-generated manifest.
Hah, thanks. I was just banging my head on that newline thing.
d
djangofan

I personally think all the answers here are mis-understanding the question. The answer to this lies in the difference of how spring-boot builds the .jar. Everyone knows that Spring Boot sets up a manifest like this, which varies from everyones asssumption that this is a standard .jar launch, which it may or may not be :

Start-Class: com.myco.eventlogging.MyService
Spring-Boot-Classes: BOOT-INF/classes/
Spring-Boot-Lib: BOOT-INF/lib/
Spring-Boot-Version: 1.4.0.RELEASE
Created-By: Apache Maven 3.3.9
Build-Jdk: 1.8.0_131
Main-Class: org.springframework.boot.loader.JarLauncher

Perhaps it needs to executed with org.springframework.boot.loader.JarLauncher on the classpath?


This sounds promising. How exactly do you add JarLauncher to the classpath?
K
KarthikPon

I faced the same issue and it's fixed now:) Just follow the below steps and the error could be for anything, but the below steps makes the process smoother. I spend lot of time to find the fix.

1.Try restart the Eclipse (if you are using Eclipse to built JAR file) --> Actually this helped my issue in exporting the JAR file properly.

2.After eclipse restart, try to see if your eclipse is able to recognize the main class/method by your Java project --> right click --> Run as --> Run configurations --> Main --> click Search button to see if your eclipse is able to lookup for your main class in the JAR file. --> This is for the validation that JAR file will have the entry point to the main class.

After this, export your Java Dynamic project as "Runnable JAR" file and not JAR file. In Java launch configuration, choose your main class. Once export the jar file, use the below command to execute. java -cp [Your JAR].jar [complete package].MainClass eg: java -cp AppleTCRuleAudit.jar com.apple.tcruleaudit.classes.TCRuleAudit You might face the unsupported java version error. the fix is to change the java_home in your shell bash profile to match the java version used to compile the project in eclipse.

Hope this helps! Kindly let me know if you still have any issues.


D
Dave Beauchesne

I found a new solution to bad manifest generation !

Open the jar file with a zip editor like WinRAR Click on for META-INF Add or edit Add: Create a text file called MANIFEST.MF in a folder called META-INF and add the following line: Manifest-Version: 1.0 Main-Class: package.ex.com.views.mainClassName Save the file and add it to the zip Edit: Drag the file out modify the MANIFEST.MF to add the previous line Open cmd and type: java -jar c:/path/JarName.jar

It should work fine now !


D
Darshil Shah

I tried this and it worked for me. mvn clean install package should work.

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <executions>
            <execution>
                <goals>
                    <goal>repackage</goal>
                </goals>
            </execution>
            </executions>
        </plugin>
    </plugins>
</build>

S
Shekh Akther

Any executable jar file Should run either by clicking or running using command prompt like java -jar app.jar (use "if path of jar contains space" - i.e. java -jar "C:\folder name\app.jar"). If your executable jar is not running, which means it is not created properly.

For better understanding, extract the jar file (or view using any tool, for windows 7-Zip is nice one) and check the file under /META-INF/MANIFEST.MF. If you find any entry like

Main-Class: your.package.name.ClaaswithMain - then it's fine, otherwise you have to provide it.

Be aware of appending Main-Class entry on MANIFEST.MF file, check where you are saving it!


K
Koneri

You Can Simply follow this step Create a jar file using

 jar -cfm jarfile-name manifest-filename Class-file name

While running the jar file simple run like this

 java -cp jarfile-name main-classname

k
kenorb

You might not have created the jar file properly:

ex: missing option m in jar creation

The following works:

jar -cvfm MyJar.jar Manifest.txt *.class

D
Dharman

For my case the problem is <pluginManagement> under <build> makes things cannot work properly.

My original pom.xml:

<build>
  <pluginManagement>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
        ...
        ...
        ...
  </pluginManagement>
</build>

After removing <pluginManagement>, the error is gone.


Thanks a lot, that did the trick!
N
Neeraj Bhatnagar

For me this error occurred simply because I forgot tell Eclipse that I wanted a runnable jar file and not a simple library jar file. So when you create the jar file in Eclipse make sure that you click the right radio button


m
mwag

The above answers were only partly helpful for me. java -cp was part of the answer, but I needed more specific info on how to identify the class to run. Here is what worked for me:

Step 1: find the class I need to run

jar tf /path/to/myjar.jar | more

The top lines of the result were:

META-INF/
META-INF/MANIFEST.MF
somepath/
somepath/App.class
META-INF/maven/
...

App.class contained the main class to run. I'm not 100% sure if you can always assume the class you need is the first one, but it was for me. If it isn't, I'd imagine it isn't too hard to use grep to exclude library-related results to pare the class list down to a manageable size.

From there it was easy: I just use that path (minus the ".class" suffix):

java -cp /path/to/myjar.jar somepath/App

It isn't always the first class. Hardly ever. Command line should be java -cp ... somepackage.App.
F
Fan Yer

Since you've add MANIFEST.MF, I think you should consider the order of Field in this file. My env is java version "1.8.0_91"

and my MANIFEST.MF as here

// MANIFEST.MF
Manifest-Version: 1.0
Created-By: 1.8.0_91 (Oracle Corporation)
Main-Class: HelloWorldSwing

// run
~ java -jar HelloWorldSwing.jar
no main manifest attribute, in HelloWorldSwing.jar

However, this as below run through

Manifest-Version: 1.0
Main-Class: HelloWorldSwing
Created-By: 1.8.0_91 (Oracle Corporation)

//this run swing normally

Eh? The order is immaterial. Unclear what you're claiming.
M
MichaelT

(first post - so it may not be clean)

This is my fix for OS X 11.6, Maven-based Netbeans 8.2 program. Up to now my app is 100% Netbeans - no tweaking (just a few shell escapes for the impossible!).

Having tried most all of the answers here and elsewhere to no avail, I returned to the art of "use what works".

The top answer here (olivier-refalo thanx) looked like the right place to start but didn't help.

Looking at other projects which did work, I noticed some minor differences in the manifest lines:

addClasspath, classpathPrefix were absent (deleted them) mainClass was missing the "com." (used the NB -> Project Properties->Run->Main Class->Browse to specify)

Not sure why (I am only 3 months into java) or how, but can only say this worked.

Here is just the modified manifest block used:

    <manifest>
        <mainClass>mypackage.MyClass</mainClass>
    </manifest>

R
Reihan_amn

Just to make one point clear about

Main-Class: <packagename>.<classname>

If you don't have package you have to ignore that part, like this:

Main-Class: <classname>

Is there anything wrong here that I am getting down vote?!