"no main manifest attribute" error when running JAR file from Maven-based Java application

### Apache NetBeans version

Apache NetBeans 30

### What happened

Maven-based Java application projects run correctly in the IDE, but print a "no main manifest attribute" error (and do nothing else) when run from the command line. This occurs even if the project's "Run" property is set to the class containing `main()` and the project rebuilt.

A workaround found on the web (see "Anything Else" section) fixes the problem. The fix is to write additional entries to the "pom.xml" file.

It appears setting the "Run" property should write these entries to the "pom.xml" file, but NetBeans does not do this.

### Language / Project Type / NetBeans Component

_No response_

### How to reproduce

In NetBeans: choose `New Project > Java with Maven > Java Application`, and fill in fields:

Project Name : Hello [fill this in]
Project Location: /home/${userID}/NetBeansProjects [default]
Project Folder : ${ProjectLocation}/Hello [generated from Project Name]
Group Id : Example [fill this in]
Version : 1.0-SNAPSHOT [default]
Package : example.hello [generated from Group Id and Project Name]
Click "OK"
> Result: A new project is created with a default "Hello World" program already coded.

In NetBeans: choose `Run > Clean and Build Project`
> Result: The project builds successfully

In a terminal window: `cd` to the project directory and the "target" subdirectory.
> Result: you are in a directory containing "Hello-1.0-SNAPSHOT.jar".

Give the command `java -jar Hello-1.0-SHAPSHOT.jar`.
> Expected result: prints "Hello World!"
> Actual result : prints "no main manifest attribute, in Hello-1.0-SNAPSHOT.jar" (and nothing else)

Some searching found this page in the NetBeans documentation: ["Packaging and Distributing Java Desktop Applications"](https://netbeans.apache.org/tutorial/main/kb/docs/java/javase-deploy/). It is outdated (building a project does not create "dist" and "build" folders as claimed), however the section "Setting the Main Class" seems applicable. So ...

In NetBeans: Right-click on the "Hello" project > choose "Properties" > click "Run", and fill in fields:

Configuration : [already filled in with this]
Main Class : use "Browse" button, choose "example.hello.Hello"
Arguments : [blank, default]
Working Directory: [blank, default]
VM Options : [blank, default]

Click "OK"
> Result:
> "pom.xml" contents unchanged
> new file "nbactions.xml" added (contents below)

In NetBeans, do a "Clean and Build" of project, then on the command line run the resulting jar.
> Result: same as before ("no main manifest attribute ..." message and nothing else).

### Did this work correctly in an earlier version?

No / Don't know

### Operating System

Linux Mint 22.1 Xia base: Ubuntu 24.04 noble

### JDK

openjdk version "21.0.10" 2026-01-20 / OpenJDK Runtime Environment (build 21.0.10+7-Ubuntu-124.04) / OpenJDK 64-Bit Server VM (build 21.0.10+7-Ubuntu-124.04, mixed mode, sharing)

### Apache NetBeans packaging

Apache NetBeans binary zip

### Anything else

Workaround
This workaround is from the site "https://www.javathinking.com/blog/netbeans-maven-project-not-adding-main-class-to-manifest/". Curiously, it matches the instructions from documentation page listed above. However, it goes an extra step and shows what should have been added to the project section in the "pom.xml" file. Putting in the class path to the main class solves the problem. The program builds and runs as expected, printing "Hello World!".

org.apache.maven.plugins
maven-jar-plugin
3.2.0



example.hello.Hello

Desired changes
If a "Java with Maven | Java Application" project has a single `main()` method in it, NetBeans should build a "pom.xml" file that will create a runnable JAR file when the project is built. This is the most reasonable expectation from a user.

If such a project has no `main()` method, or multiple `main()` methods, NetBeans should alert the user to this and suggest possible actions when the project is built.

Otherwise, NetBeans' behavior or documentation should change so that a user can build a runnable JAR file with minimumal fuss or documentation searching.
- Preferably this would be a clearly surfaced option during project creation.
- Next best would be a dialog shown at the time of first build in which a user could set options for remaining builds.
- At the very least, when a user updates the "Main Class" field of the project's "Run" property, a section similar to that in the workaround above should appear in the project's "pom.xml" file. I suspect this is the currently designed behavior of NetBeans, and it is a bug that this does not happen.

From the NetBeans "About" window

Product Version: Apache NetBeans IDE 30
Java: 21.0.10; OpenJDK 64-Bit Server VM 21.0.10+7-Ubuntu-124.04
Runtime: OpenJDK Runtime Environment 21.0.10+7-Ubuntu-124.04
System: Linux version 6.8.0-117-generic running on amd64; UTF-8; en_US (nb)
User directory: /home/dwight/.netbeans/30
Cache directory: /home/dwight/.cache/netbeans/30

Project's "pom.xml" file contents

4.0.0
Example
Hello
1.0-SNAPSHOT
jar

UTF-8
21
example.hello.Hello

Project's "pom.xml" file contents with workaround
Note: the maven-jar-plugin version is from the workaround on the web. NetBeans should fill it in with an appropriate value.

4.0.0
Example
Hello
1.0-SNAPSHOT
jar

UTF-8
21
example.hello.Hello




org.apache.maven.plugins
maven-jar-plugin
3.2.0



example.hello.Hello

Project's "nbactions.xml" file contents

run

jar


process-classes
org.codehaus.mojo:exec-maven-plugin:3.5.1:exec



${exec.vmArgs} -classpath %classpath ${exec.mainClass} ${exec.appArgs}

example.hello.Hello
java



debug

jar


process-classes
org.codehaus.mojo:exec-maven-plugin:3.5.1:exec


-agentlib:jdwp=transport=dt_socket,server=n,address=${jpda.address}
${exec.vmArgs} -classpath %classpath ${exec.mainClass} ${exec.appArgs}

example.hello.Hello
java
true



profile

jar


process-classes
org.codehaus.mojo:exec-maven-plugin:3.5.1:exec



${exec.vmArgs} -classpath %classpath ${exec.mainClass} ${exec.appArgs}
example.hello.Hello
java

$ java -version

openjdk version "21.0.10" 2026-01-20
OpenJDK Runtime Environment (build 21.0.10+7-Ubuntu-124.04)
OpenJDK 64-Bit Server VM (build 21.0.10+7-Ubuntu-124.04, mixed mode, sharing)

$ mvn --version

Apache Maven 3.8.7
Maven home: /usr/share/maven
Java version: 21.0.10, vendor: Ubuntu, runtime: /usr/lib/jvm/java-21-openjdk-amd64
Default locale: en_US, platform encoding: UTF-8
OS name: "linux", version: "6.8.0-117-generic", arch: "amd64", family: "unix"

$ ~/opt/netbeans/bin/netbeans --list

Detected 2x HiDPI scaling in Xft.dpi setting; setting GDK_SCALE=2
WARNING: package com.sun.java.swing.plaf.windows not in java.desktop
WARNING: package com.apple.laf not in java.desktop
Need to use also --modules, --refresh

$ ~/opt/netbeans/platform/lib/nbexec --list --modules --refresh

May 24, 2026 11:40:14 AM org.netbeans.ProxyURLStreamHandlerFactory register
SEVERE: No way to find original stream handler for jar protocol
java.lang.reflect.InaccessibleObjectException: Unable to make field transient java.net.URLStreamHandler java.net.URL.handler accessible: module java.base does not "opens java.net" to unnamed module @13221655
at java.base/java.lang.reflect.AccessibleObject.throwInaccessibleObjectException(AccessibleObject.java:391)
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:367)
at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:315)
at java.base/java.lang.reflect.Field.checkCanSetAccessible(Field.java:183)
at java.base/java.lang.reflect.Field.setAccessible(Field.java:177)
at org.netbeans.ProxyURLStreamHandlerFactory.register(ProxyURLStreamHandlerFactory.java:59)
at org.netbeans.JarClassLoader.(JarClassLoader.java:131)
at org.netbeans.MainImpl.execute(MainImpl.java:166)
at org.netbeans.MainImpl.main(MainImpl.java:60)
at org.netbeans.Main.main(Main.java:58)

java.io.FileNotFoundException: /var/cache/lastModified/all-checksum.txt (No such file or directory)
at java.base/java.io.FileOutputStream.open0(Native Method)
at java.base/java.io.FileOutputStream.open(FileOutputStream.java:289)
at java.base/java.io.FileOutputStream.(FileOutputStream.java:230)
at java.base/java.io.FileOutputStream.(FileOutputStream.java:179)
at org.netbeans.Stamps.compareAndUpdateFile(Stamps.java:449)
at org.netbeans.Stamps.stamp(Stamps.java:342)
at org.netbeans.Stamps.moduleJARs(Stamps.java:285)
at org.netbeans.Stamps.file(Stamps.java:175)
at org.netbeans.Stamps.asByteBuffer(Stamps.java:180)
at org.netbeans.Stamps.asByteBuffer(Stamps.java:160)
at org.netbeans.Archive.(Archive.java:95)
at org.netbeans.JarClassLoader.initializeCache(JarClassLoader.java:98)
at org.netbeans.MainImpl$BootClassLoader.run(MainImpl.java:331)
at org.netbeans.CLIHandler.initialize(CLIHandler.java:573)
at org.netbeans.CLIHandler.initialize(CLIHandler.java:359)
at org.netbeans.MainImpl.execute(MainImpl.java:181)
at org.netbeans.MainImpl.main(MainImpl.java:60)
at org.netbeans.Main.main(Main.java:58)
Code Name Version State
------------------------------------------- -------- ---------
org.netbeans.modules.core.kit 1.63 Enabled
org.netbeans.libs.junit4 1.50 Installed
org.netbeans.libs.junit5 1.29 Installed
org.netbeans.swing.plaf 1.74 Enabled
org.netbeans.modules.autoupdate.services 1.88 Enabled
org.netbeans.html.presenters.spi 1.8.2 Installed
org.netbeans.modules.options.api 1.77 Enabled
org.netbeans.core.network 1.44 Enabled
org.netbeans.api.search 1.53 Installed
org.openide.modules 7.80 Enabled
org.openide.filesystems.nb 9.42 Enabled
org.netbeans.modules.keyring 1.56 Enabled
org.netbeans.core.windows 2.117 Enabled
org.netbeans.api.templates 1.40 Enabled
org.openide.util.lookup 8.66 Enabled
org.netbeans.swing.laf.flatlaf 1.25 Enabled
org.netbeans.modules.masterfs.nio2 1.47 Enabled
org.netbeans.modules.autoupdate.cli 1.46 Enabled
org.netbeans.modules.uihandler 2.67 Installed
org.netbeans.api.annotations.common 1.60 Enabled
org.netbeans.modules.janitor 1.25 Enabled
org.netbeans.modules.templatesui 1.35 Installed
org.netbeans.core.output2 1.74 Enabled
org.netbeans.core.netigso 1.63 Enabled
org.netbeans.libs.jna.platform 2.27 Enabled
org.netbeans.bootstrap 2.111 Enabled
org.openide.execution 9.35 Installed
org.netbeans.modules.htmlui 1.17 Installed
org.netbeans.modules.print 7.58 Enabled
org.netbeans.spi.quicksearch 1.59 Enabled
org.openide.util 9.40 Enabled
org.netbeans.modules.spi.actions 1.60 Installed
org.openide.windows 6.109 Enabled
org.apache.commons.logging 1.3.5 Installed
org.netbeans.modules.autoupdate.ui 1.78 Enabled
org.apache.commons.codec 1.21.0 Installed
org.netbeans.modules.sampler 1.46 Enabled
org.netbeans.core.io.ui 1.62 Enabled
org.netbeans.html.xhr4j 1.8.2 Installed
org.netbeans.api.progress.compat8 1.79 Installed
org.openide.dialogs 7.79 Enabled
org.netbeans.modules.templates 1.39 Enabled
org.openide.awt 7.100 Enabled
org.openide.actions 6.71 Enabled
org.openide.compat 6.72 Installed
org.netbeans.api.io 1.35 Enabled
org.netbeans.api.intent 1.34 Enabled
org.openide.loaders 7.102 Enabled
org.openide.nodes 7.77 Enabled
org.netbeans.modules.keyring.fallback 1.40 Enabled
org.netbeans.swing.outline 1.66 Enabled
org.netbeans.api.progress.nb 1.80 Enabled
org.openide.io 1.81 Enabled
net.java.html.sound 1.8.2 Installed
org.netbeans.api.progress 1.80 Enabled
org.openide.util.ui 9.41 Enabled
net.java.html.geo 1.8.2 Installed
org.openide.util.ui.svg 1.26 Enabled
org.netbeans.libs.testng 1.46 Installed
org.netbeans.libs.javafx 2.39 Installed
org.openide.text 6.101 Enabled
org.netbeans.libs.asm 5.35 Enabled
org.netbeans.libs.osgi 1.54 Enabled
org.netbeans.libs.flatlaf 1.26 Enabled
org.netbeans.modules.masterfs.linux 1.45 Enabled
org.netbeans.modules.favorites 1.78 Enabled
org.netbeans.modules.options.keymap 1.69 Enabled
net.java.html.json 1.8.2 Installed
org.netbeans.core.startup 1.95.0.1 Enabled
org.apache.commons.commons_io 2.23 Installed
org.netbeans.modules.queries 1.75 Enabled
org.netbeans.core.execution 1.74 Installed
org.netbeans.libs.javax.inject 2.67 Installed
org.netbeans.modules.editor.mimelookup 1.72 Enabled
org.netbeans.core 3.83 Enabled
org.netbeans.swing.laf.dark 2.27.0.2 Enabled
org.netbeans.modules.sendopts 2.68 Enabled
net.java.html.boot 1.8.2 Installed
net.java.html.boot.script 1.8.2 Installed
org.netbeans.libs.felix 2.47 Enabled
org.netbeans.modules.progress.ui 1.65 Enabled
org.netbeans.core.nativeaccess 1.63 Enabled
org.netbeans.modules.junitlib 1.37 Installed
org.netbeans.modules.masterfs.ui 2.35.0.2 Enabled
org.netbeans.core.multiview 1.76 Installed
org.netbeans.modules.settings 1.81 Enabled
net.java.html.boot.fx 1.8.2 Installed
org.netbeans.api.visual 2.80 Installed
org.netbeans.modules.masterfs 2.87.0.2 Enabled
org.netbeans.lib.uihandler 1.77 Installed
org.netbeans.modules.keyring.impl 1.56 Enabled
net.java.html 1.8.2 Installed
org.openide.explorer 6.94 Enabled
org.openide.filesystems.compat8 9.41 Enabled
org.netbeans.libs.jsvg 2.4 Enabled
org.netbeans.core.multitabs 1.44.0.1 Enabled
org.netbeans.modules.editor.mimelookup.impl 1.64 Enabled
org.openide.filesystems 9.45 Enabled
org.netbeans.core.osgi 1.54 Installed
org.netbeans.api.scripting 1.29 Enabled
org.netbeans.api.htmlui 1.40 Installed
org.netbeans.modules.netbinox 1.73 Installed
org.netbeans.swing.tabcontrol 1.89 Enabled
org.netbeans.api.dashboard 0.9 Installed
org.netbeans.libs.jna 2.27 Enabled
org.netbeans.html.ko4j 1.8.2 Installed
org.netbeans.core.ui 1.77 Enabled
org.apache.commons.lang3 3.17.0 Installed
org.netbeans.core.startup.base 1.94.0.1 Enabled
org.netbeans.modules.javahelp 2.73 Installed
org.openide.execution.compat8 9.34 Installed
org.netbeans.libs.jsr223 1.67 Installed
------------------------------------------- -------- ---------

### Are you willing to submit a pull request?

No

Reproduce the Java with Maven project flow described in the issue, then compare the generated pom.xml and nbactions.xml after setting the Run property's Main Class. Start by tracing how the Maven project template and Run properties are handled; done means the intended behavior is verified and a clean build produces a command-line runnable JAR, or the limitation is clearly documented.

Written by the indexing model from the issue text.