Solve Error Could not reserve enough space for object heap

So in this article, We’ll see how to solve the error “Could not reserve enough space for object heap”. While solving this error you will be also able to solve the following errors which occurs due to the same reasons:

  • Error Occurred during initialization of VM
  • Could not allocate metaspace
  • Unable to allocate bitmaps for parallel garbage collection for the requested heap
  • Could not create the Java virtual machine

Reasons for this Error

The above following errors are usually raised when the Java process is unable to create the Java virtual machine because of the memory limitations or constraints encountered on the running system. Most of the time it occurs on the 32-bit  Java Virtual Machine.

So there are two possible reasons that error has been encountered-

  • First, when we run a java program with Xmx (max heap size limit parameter) and passing the value which is greater than the value that we can set to a process in that operating system.
  • Second, when we are giving the right size for Xmx but there are other applications running the system which are occupying the space of memory. Due to those applications, The java process can’t occupy the space it needed.


  • As mentioned above, most of the time this problem occurs on the 32-bit JVM. So there is a possibility that if we switch to 64-bit JVM than this problem will be solved.
  • As the other reasons were due to memory constraints, So we can solve those by setting a lower heap size limit parameter while running our Application which should be greater than the size your application needed and less than the size we have available in our memory. You can set the heap size while running your application as mentioned below:

java -Xmx512M MyApplication

  • And in case you don’t want to set the heap size limit parameter each time you run the program then you can also set it globally by setting the environment variables –
    • For Windows – You can directly search for environment variables in the search bar or you can right-click on this pc icon -> click on the properties -> click on Advanced system settings -> click on Environment Variables and add a new system variable with name _JAVA_OPTIONS and give it the value -Xmx512M .
    • For Linux – Open your .bashrc file as administrator and add the following line at the last of the file –

export _JAVA_OPTIONS=”-Xmx512M”


So, these were the main reasons for the error “could not reserve enough space for object heap” and we have provided the possible solutions. Let us know in the comment section which solution worked for you.

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