What are mig21.dat Error Messages?

Dynamic Link Library mig21.dat Errors

mig21.dat is considered a type of Dynamic Link Library (DLL) file. Dynamic Link Library files, like mig21.dat, are essentially a "guide book" that stores information and instructions for executable (EXE) files - like AppInstaller.exe - to follow. These files were created so that multiple programs (eg. YS Flight Simulator) could share the same mig21.dat file, saving valuable memory allocation, therefore making your computer run more efficiently.

Unfortunately, what makes DLL files so convenient and efficient, also makes them extremely vulnerable to problems. If something happens to a shared DAT file, either it goes missing or gets corrupted in some way, it can generate a "runtime" error message. Runtime is pretty self-explanatory; it means that these errors are triggered when mig21.dat is attempted to be loaded either when YS Flight Simulator is starting up, or in some cases already running. Some of the most common mig21.dat errors include:

• Access Violation at address - mig21.dat.
• mig21.dat could not be found.
• Cannot find C:\YsflightForWindows_R8366\Ysflight\aircraft\mig21.dat.
• Cannot register mig21.dat.
• Cannot start YS Flight Simulator. A required component is missing: mig21.dat. Please install YS Flight Simulator again.
• Failed to load mig21.dat.
• The application has failed to start because mig21.dat was not found.
• The file mig21.dat is missing or corrupt.
• This application failed to start because mig21.dat was not found. Re-installing the application may fix this problem.

Your mig21.dat file could be missing due to accidental deletion, uninstalled as a shared file of another program (shared with YS Flight Simulator), or deleted by a malware infection. Furthermore, mig21.dat file corruption could be caused from a power outage when loading YS Flight Simulator, system crash while loading mig21.dat, bad sectors on your storage media (usually your primary hard drive), or quite commonly, a malware infection. Thus, it's critical to make sure your anti-virus is kept up-to-date and scanning regularly.

How to Fix mig21.dat Errors in 3 Steps (Time to complete: ~5-15 minutes)

If you're encountering one of the error messages above, follow these troubleshooting steps to resolve your mig21.dat issue. These troubleshooting steps are listed in the recommended order of execution.

To begin System Restore (Windows XP, Vista, 7, 8, and 10):

1. Hit the Windows Start button
2. When you see the search box, type "System Restore" and press "ENTER".
3. In the search results, find and click System Restore.
4. Please enter the administrator password (if applicable / prompted).
5. Follow the steps in the System Restore Wizard to choose a relevant restore point.
6. Restore your computer to that backup image.

If the Step 1 fails to resolve the mig21.dat error, please proceed to the Step 2 below.

You can uninstall YS Flight Simulator software by following these instructions (Windows XP, Vista, 7, 8, and 10):

1. Hit the Windows Start button
2. In the search box, type "Uninstall" and press "ENTER".
3. In the search results, find and click "Add or Remove Programs"
4. Find the entry for YS Flight Simulator 20181124 and click "Uninstall"
5. Follow the prompts for uninstallation.

After the software has been fully uninstalled, restart your PC and reinstall YS Flight Simulator software.

If this Step 2 fails as well, please proceed to the Step 3 below.

YS Flight Simulator 20181124

YSFlight

When the first two steps haven't solved your issue, it might be a good idea to run Windows Update. Many mig21.dat error messages that are encountered can be contributed to an outdated Windows Operating System. To run Windows Update, please follow these easy steps:

1. Hit the Windows Start button
2. In the search box, type "Update" and press "ENTER".
3. In the Windows Update dialog box, click "Check for Updates" (or similar button depending on your Windows version)
4. If updates are available for download, click "Install Updates".
5. After the update is completed, restart your PC.

If Windows Update failed to resolve the mig21.dat error message, please proceed to next step. Please note that this final step is recommended for advanced PC users only.

If Those Steps Fail: Download and Replace Your mig21.dat File (Caution: Advanced)

If none of the previous three troubleshooting steps have resolved your issue, you can try a more aggressive approach (Note: Not recommended for amateur PC users) by downloading and replacing your appropriate mig21.dat file version. We maintain a comprehensive database of 100% malware-free mig21.dat files for every applicable version of YS Flight Simulator. Please follow the steps below to download and properly replace you file:

1. Locate your Windows operating system version in the list of below "Download mig21.dat Files".
2. Click the appropriate "Download Now" button and download your Windows file version.
3. Copy this file to the appropriate YS Flight Simulator folder location:
   
   Windows 10: C:\YsflightForWindows_R8366\Ysflight\aircraft\
   
4. Restart your computer.

If this final step has failed and you're still encountering the error, you're only remaining option is to do a clean installation of Windows 10.

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