MTA:SA fix

CL30: Data file is missing or modified. Possible virus activity

At start, MTA shows CL30: one of its own data files is missing or was changed, and it says this may be virus activity. Run a full virus scan first, then reinstall MTA.

Codes on this page: CL30

Steps

1. Read which file it names

   The message names one file and says if it is missing or modified. MTA looks for that file in the mta folder inside your MTA installation folder.

   Source: MTA source code

2. Make sure an anti-virus is running

   If no anti-virus is running on your PC, install one. MTA's help page lists free ones: Bitdefender Antivirus Free, Avast Free Antivirus, AVG AntiVirus Free and Malwarebytes Free.

   Source: MTA help

3. Update it and scan the whole PC

   Update your anti-virus and check that real-time scanning is on. Then run a complete virus scan of the computer.

   Source: MTA help

4. Reinstall MTA

   Install Multi Theft Auto again. MTA's help page links one installer for Windows 10 and 11, and another for Windows 7 and 8.x.

   Source: MTA help

5. Start MTA again

   Start MTA and see if the message is gone.

   Source: MTA help

See also: CL29: client integrity warning at launch, MTA data files or core.dll are missing, MTA warns that it could not detect an anti-virus, MTA terminated due to an integrity violation

Still not fixed? Copy the whole message, not only the code, and check your log in the Fix tool. It is read on your own computer.

Other problems like this

• CL38: Error loading netc.dll module
• CL13: GTA path contains unsupported (unicode) characters
• CL01: MTA:SA could not complete the following task (Administrator access)
• CL33: Main file has an incorrect name
• Sorry, game not found: MTA cannot find GTA San Andreas
• Antivirus says MTA is a virus, or GTA:SA executable is incorrect or missing

All fix guides · Every MTA:SA error code · Crash codes and offsets