PLS-00103: Encountered the symbol " " when expecting one of the following - oracle

Question

For some reason this wont work. I have got it down to the most basic operation to try and troubleshoot.
BEGIN
FOR rec IN (
select REGISTRATION_UID from DIM_REGISTRATION_SET
) 
   LOOP
dbms_output.put_line('Testing 123');
  END LOOP; 
end;
/
My error is as below:
Error starting at line 1 in command:
BEGIN
FOR rec IN (
select REGISTRATION_UID from DIM_REGISTRATION_SET
) 
   LOOP
dbms_output.put_line('Testing 123');
  END LOOP; 
end;
Error report:
ORA-06550: line 4, column 6:
PLS-00103: Encountered the symbol " " when expecting one of the following:
loop
06550. 00000 - "line %s, column %s:\n%s"
*Cause: Usually a PL/SQL compilation error.
*Action:

Answer 1

You seem to have an unexpected character in your code. If you copy and paste the rendered output from this question then it runs fine. If you copy the question source code (from the edit dialogue) then it gets that error.
Dumping the code (again copied from the source, not the rendering) shows:
select dump('(
select REGISTRATION_UID from DIM_REGISTRATION_SET
) ', 16)
from dual; 
DUMP('(SELECTREGISTRATION_UIDFROMDIM_REGISTRATION_SET) ',16)
--------------------------------------------------------------------------------
Typ=96 Len=73: 28,a,20,20,20,20,20,20,20,20,20,20,73,65,6c,65,63,74,20,52,45,47,
49,53,54,52,41,54,49,4f,4e,5f,55,49,44,20,66,72,6f,6d,20,44,49,4d,5f,52,45,47,49
,53,54,52,41,54,49,4f,4e,5f,53,45,54,a,20,20,20,20,20,20,20,20,29,c2,a0
So the space after the closing parenthesis isn't actually a space, it's Unicode character c2a0, which is a non-breaking space.
The error message shows that too, if you dump that:
select dump ('Encountered the symbol " "', 16) from dual;
DUMP('ENCOUNTEREDTHESYMBOL" "',16)
--------------------------------------------------------------------------------
Typ=96 Len=27: 45,6e,63,6f,75,6e,74,65,72,65,64,20,74,68,65,20,73,79,6d,62,6f,6c
,20,22,c2,a0,22
I would guess you copied that code from somewhere (Word?) and it picked up that character, and it hasn't been translated to a normal space. Just replace it with a space, or remove it as it's redundant whitespace anyway.
Actually, there are several others; two at the start of the LOOP line (followed by two normal spaces), and two immediately before END LOOP; (preceded by two normal spaces), and one after that statement; so those all need to be replaced too. (I'd be tempted to retype the whole thing, but that might not be practical for your full code).