Why doesn't WebStorm launch if I change VM options I've changed VM options in ~/.WebStorm2016.3/webstorm.exe.vmoptions through Help -> Edit custom VM options menu to the following:
# custom WebStorm VM options

-server
-Xms740m   <
-Xmx3050m  <
-XX:ReservedCodeCacheSize=240m
-XX:+UseConcMarkSweepGC
-XX:SoftRefLRUPolicyMSPerMB=50
-ea
-Dsun.io.useCanonCaches=false
-Djava.net.preferIPv4Stack=true
-XX:+HeapDumpOnOutOfMemoryError
-XX:-OmitStackTraceInFastThrow

After that, WebStorm is not launching. Why?


After that, WebStorm is not launching. Why?

That's because Java (JVM?) is unable to allocate that much memory (3GB; which needs to be done in 1 solid chunk .. that's is very problematic when using 32-bit JDK).
Better switch to using 64-bit JDK and 64-bit WebStorm launcher which can handle such situations if you need that much memory.
If you need more info on that -- please check this StackOverflow question and those that offered in Related section: Java 32bit Xmx vs java 64bit Xmx .
Other links to the actual JetBrains' articles on this/related subject:


*

*https://intellij-support.jetbrains.com/hc/en-us/articles/207241105-The-JVM-could-not-be-started-The-main-method-may-have-thrown-an-exception

*https://intellij-support.jetbrains.com/hc/en-us/articles/206544869-Configuring-JVM-options-and-platform-properties

If you do not know how to start using 64-bit WebStorm, please check this arcticle or just use 2017.1 EAP build -- from 2017.1 JetBrains IDEs come with and use own 64-bit JDK by default.
If anything -- check idea.log for details (or Help | About) -- it should have bit info there.
Alternatively:


*

*Help | Find Action...

*Search for Switch IDE boot JDK... action (typing just jdk should be enough to have that action preselected) and run that action 

*Do the needed changes there