LSL Errors

Run-time error messages

A script may stop running, and chat at you the complaint "Script run-time error", followed by another complaint such as:

Script run-time error: Heap Error

Don't be evil. For example, don't return a list of one entry that is the result of a routine that returns no result.

Script run-time error: Lists may not contain lists

Don't try adding a list into a list.

Script run-time error: Math Error

Float divided by zero, integer divided by zero, etc.

Script run-time error: Stack-Heap Collision

The Stack has collided with the Bytecode or the Heap.

Each script runs inside 16 KiB of memory divided out among Bytecode, Stack, and Heap.

You can cause collision by compiling too much script, which produces too much Bytecode. The script compiles and saves successfully, but when you rez an object containing the script, the script crashes, immediately or while running.

See llGetFreeMemory.

Example Scripts

Compile and run examples like these to experience the script run-time errors.

default
{
    state_entry()
    {
        llOwnerSay((string) [llOwnerSay("bye")]); // Script run-time error: Heap Error
    }
}

default
{
    state_entry()
    {
        list once = [];
        list twice = [once, once]; // Script run-time error: Lists may not contain lists
    }
}

default
{
    state_entry()
    {
        float one = 1.0;
        float zero = 0.0;
        float quotient = one / zero; // Script run-time error: Math Error
        llOwnerSay((string) quotient);
    }
}

default
{
    state_entry()
    {
        list entries = [0];
        while (TRUE)
        {
            entries += entries; // Script run-time error: Stack-Heap Collision
            llOwnerSay((string) llGetListLength(entries));
        }
    }
}

Compile-time error messages

The SL GUI may reject some code that you feel is perfectly clear, printing ERROR at you and then explaining with some further complaint.

ERROR: Type mismatch

You must name the .x .y .z .s components of a vector or rotation that you're assigning, you can't assign them all at once from a list, for instance:

default
{
    state_entry()
    {
        vector vec = (vector) [1, 2, 3]; // ERROR : Type mismatch
        llOwnerSay((string) vec);
    }
}

ERROR: Syntax error

The compiler complains of a "syntax" error when it doesn't like your spelling, when it doesn't like your punctuation, or it thinks you typed too much script.

How much script is too much script never should but sometimes actually does vary by operating system. Linux, Mac OS X, and Windows reported different limits in 2007-08, so at that time you could run a script that you cannot edit without switching operating systems.

For example, once upon a time, Mac OS X could compile twenty-five cascaded else-if's, and Windows could not:

demoElseIfSyntaxError(integer count)
{
    if (count == 0)
    {
        ;
    }
    else if (count == 1)
    {
        ;
    }
    else if (count == 2)
    {
        ;
    }
    ...
    else if (count == 25)
    {
        ;
    }
}

Note: In effect, an astonishing compiler bug of this kind is a copy-restriction mechanism, preventing only people who have the buggy compiler from editing the source.