Java Refuses to Start - Could Not Reserve Enough Space For Object Heap

Could not reserve enough space for object heap

Run the JVM with -XX:MaxHeapSize=512m (or any big number as you need) (or -Xmx512m for short)

Java: Could not reserve enough space for object heap error, despite enough memory

The JVM can't just pick any old memory anywhere for its object heap, it has to be contiguous; meaning a continuous, unfragmented block of free memory. While you theoretically might have enough raw memory free to launch a JVM with this heap size, if it's not contiguous then it's useless as far as the JVM is concerned.

Note that this is far, far more likely to happen with a 32 bit address space (if you're using a 32 bit OS or 32 bit JVM), but can of course still happen regardless.

Could not reserve enough space for object heap to start JVM

It looks like the machine you're trying to run this on has only 256 MB memory.

Maybe the JVM tries to allocate a large, contiguous block of 64 MB memory. The 192 MB that you have free might be fragmented into smaller pieces, so that there is no contiguous block of 64 MB free to allocate.

Try starting your Java program with a smaller heap size, for example:

java -Xms16m ...

Intellij occasionally unable to reserve enough space for object heap

Ultimately I was able to resolve the issue by updating the proper JDK.
My project was picking up on an incorrect JDK and hence was running the 32 Bit as opposed to 64 bit JDK.

Simply added the correct JDK under File > Project Settings.

It seemed that my project never required that much memory before, but once the need had risen, it seems that a 64 bit became required.

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