Eclipse returns error message "Java was started but returned exit code = 1"

Question

The error message points to a problem with your Java version. Do you have a JDK installed?

Try adding the following (noting the new line):

/!\ make sure, that the -vm option occurs before the -vmargs command. Everything after -vmargs is passed directly to the JVM.

-vm 
c:/wherever/java/jdk1.6.0_21/jre/bin/server/jvm.dll
-vmargs... 

...to your eclipse.ini file, pointing to the JDK you want to use, and check that the required Java version is at least as new as your JDK. This is the path for a Windows system. More on paths can be found here (scroll down).

If you don't know where the eclipse.ini file is: regularly it is in the folder of your eclipse.exe.

Edit2: @KadoLakatt: the reason why installing the latest Java Version worked for you is because Eclipse checks the standard path for a JVM if it doesn't find a -vm entry (see here). However I'd not recommend that, since you might be wrong guessing the JVM used. If you update Java (automatically?) you might run into problems in your Eclipse wondering what you might have changed. Better set it to a specific folder in your eclipse.ini to be certain.

I received this error out of the blue. Eclipse stopped working even though I made no config changes and did not install any new jdk's.

Here was my eclipse.ini file :

--clean
-startup
plugins/org.eclipse.equinox.launcher_1.3.0.v20130327-1440.jar
--launcher.library
plugins/org.eclipse.equinox.launcher.win32.win32.x86_1.1.200.v20130807-1835
-product
org.eclipse.epp.package.jee.product
--launcher.defaultAction
openFile
--launcher.XXMaxPermSize
256M
-showsplash
org.eclipse.platform
--launcher.XXMaxPermSize
256m
--launcher.defaultAction
openFile
-vm
C:/Program Files (x86)/Java/jre7/bin/javaw.exe
--launcher.appendVmargs
-vmargs
-Dosgi.requiredJavaVersion=1.6
-Xms40m
-Xmx1024m

To get Eclipse to start successfully I removed

    -vmargs
    -Dosgi.requiredJavaVersion=1.6
    -vm 
C:/Program Files (x86)/Java/jre7/bin/javaw.exe

So here is my updated file :

--clean
-startup
plugins/org.eclipse.equinox.launcher_1.3.0.v20130327-1440.jar
--launcher.library
plugins/org.eclipse.equinox.launcher.win32.win32.x86_1.1.200.v20130807-1835
-product
org.eclipse.epp.package.jee.product
--launcher.defaultAction
openFile
--launcher.XXMaxPermSize
256M
-showsplash
org.eclipse.platform
--launcher.XXMaxPermSize
256m
--launcher.defaultAction
openFile
-Xms40m
-Xmx1024m

I have no idea why removing osgi.requiredJavaVersion=1.6 fixed this as my jvm version is 1.6. From the doc http://help.eclipse.org/indigo/index.jsp?topic=%2Forg.eclipse.platform.doc.isv%2Freference%2Fmisc%2Fruntime-options.html

osgi.requiredJavaVersion
The minimum java version that is required to launch Eclipse. The default value is "1.4.1".

I think my java version was set correctly. Anyway Eclipse starts and runs for me now......

it can be like this as well:

-vm 
C:\Program Files\Java\jre6\bin\server\jvm.dll

Working combinations of OS, JDK and eclipse bitness.

• 32-bit OS , 32-bit JDK , 32-bit Eclipse (32-bit only)
• 64-bit OS , 32-bit JDK , 32-bit Eclipse
• 64-bit OS , 64-bit JDK , 64bit Eclipse (64-bit only)

Kindly use 1 of the above combinations.

Adding -vm parameters works for me.

-vm 
C:\Program Files\Java\jdk1.7.0_45\jre\bin\server\jvm.dll

For those of you who tried all the above answers without any success, try lowering your -Xms value. I am required to support an older Eclipse (Weblogic Eclipse 10.3.6) - I had the following .ini on my Windows 7 machine and my Windows Server 2008 R2 Enterprise VM (the Java version below points to a 32-bit Java) that had worked and were working perfectly, respectively.

-vm
C:/Java/Java7/jdk1.7.0_79/bin/javaw.exe
-startup
plugins/org.eclipse.equinox.launcher_1.3.0.v20120522-1813.jar
--launcher.library
plugins/org.eclipse.equinox.launcher.win32.win32.x86_1.1.200.v20120522-1813
-showsplash
org.eclipse.platform
--launcher.defaultAction
openFile
-vmargs
-Xms1024m
-Xmx1024m
-XX:MaxPermSize=256m
-Dsun.lang.ClassLoader.allowArraySyntax=true
-Dweblogic.home=C:/Oracle/Middleware/wlserver_10.3

So a 32-bit Java for a 32-bit Eclipse, but still exit code 1. Based on all answers I had seen here, and the only change being a new laptop with Windows 10, the only possible explanation was that the new OS and the Eclipse were disagreeing on something. So I started playing around with each of the values, and it worked when I lowered both Xms and Xmx to 512m. I have a hunch that possibly the new Windows OS is preventing a higher initial heap size based on some run condition (the higher -Xms does work on Windows 10 on all other similar devices I came across) - so any other explanation is welcome. Meanwhile following is the only value I tweaked to successfully launch Eclipse.

-Xms512m