Access violation (memory error) and some similar exceptions are trapped and fbdebugger waits on the faulty line.
You can change variable values and/or skip (not execute) the concerned instructions or terminate the program.

Example :
- Compile this piece of code.

    Dim As Integer a(1)
    Print "test"
    a(5000000)=1 'access violation
    Print "end"

-  If FBdebugger is not defined as JIT debugger, do it, start it then select/start the example exe. You get this box.

The error line is displayed with some information (Read or Write error,..).
Click on yes to continue. Then skip the current line to execute the last one by putting the cursor on print "end" and press M or click the change exec button.