MTA:SA anti-cheat code
MTA:SA anti-cheat code AC#21
MTA's anti-cheat lists this number under additional trainers.
- Code
AC#21- Where you see it
- A kick or restriction message
- MTA's own wording
- Additional trainers
- Family
- AC codes
What it means
AC is one of MTA's three anti-cheat prefixes. The number names a published detection category. MTA's own guide says a detection does not prove intent, and it does not list every detector. MTA's own documentation gives this code as Additional trainers.
How to fix it
Work down the list and stop when it is solved.
Read the whole message, then the official page
The number names a detection category, not a program on your computer. MTA's anti-cheat guide lists what each category covers, and the full message is what tells you which case you are in.
Use the official client and clean game files
Install MTA from multitheftauto.com and keep GTA unmodified. Trainers, injected DLLs and patched game files are exactly what these checks look for.
Close what the message names
If the message names a program, close it completely, then start MTA again. Some of these programs keep a background service running, so check that it has really stopped.
If you were banned, appeal where it was issued
A server ban is appealed on that server. An MTA global ban is appealed through MTA's own process. Keep the full message: it names who issued it.
MTA's anti-cheat guide publishes the category, not the detector. The guide itself says the list is incomplete and that a detection does not prove intent. Keep the whole message: the part after the code is what tells you which case you are in.
Still stuck? The Fix tool reads MTA's own log on your computer and points at the matching steps. Nothing is uploaded.
Open the Fix toolOther AC codes
- AC#1MTA's anti-cheat lists this number under health or armour manipulation.
- AC#2MTA's anti-cheat lists this number under DLL corruption.
- AC#4MTA's anti-cheat lists this number as a broad security detection.
- AC#5MTA's anti-cheat lists this number under trainers.
- AC#11MTA's anti-cheat lists this number under additional trainers.
- AC#18MTA's anti-cheat lists this number under altered game files.
Every MTA:SA error code · Crash codes and offsets
Where this comes from
Public category only; incomplete detector inventory and no finding about intent.
Meanings read from these sources on 5 September 2026 and written in our own words here.