BUG in 3.6.0 ?

[mnrvovrfc]

I expect it to be some kind of memory error.

(and Yes I know this is an array of 1.5GB, but it used to work up to 2GB)

How much RAM do you have on your computer? If less than 16GB then this shouldn't be done.

"It used to work up to 2GB" but remember that managing strings could take up to 4 times what it looks like strictly from the source code. Concatenation is the biggest offender. Function calls, even to in-built functions like MID$() could make copies of strings only to process.

The operating system needs memory for other things it has to do, including holding your memory-hogging program.

If possible you should break down the task into two or more parts.