dx9.dll is considered a type of Dynamic Link Library (DLL) file. Dynamic Link Library files, like dx9.dll, are essentially a "guide book" that stores information and instructions for executable (EXE) files - like MpSigStub.exe - to follow. These files were created so that multiple programs (eg. Euro Truck Simulator) could share the same dx9.dll 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 DLL 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 dx9.dll is attempted to be loaded either when Euro Truck Simulator is starting up, or in some cases already running. Some of the most common dx9.dll errors include:
- Access Violation at address - dx9.dll.
- dx9.dll could not be found.
- Cannot find C:\Program Files (x86)\Euro Truck Simulator\lib\dx9.dll.
- Cannot register dx9.dll.
- Cannot start Euro Truck Simulator. A required component is missing: dx9.dll. Please install Euro Truck Simulator again.
- Failed to load dx9.dll.
- The application has failed to start because dx9.dll was not found.
- The file dx9.dll is missing or corrupt.
- This application failed to start because dx9.dll was not found. Re-installing the application may fix this problem.
Your dx9.dll file could be missing due to accidental deletion, uninstalled as a shared file of another program (shared with Euro Truck Simulator), or deleted by a malware infection. Furthermore, dx9.dll file corruption could be caused from a power outage when loading Euro Truck Simulator, system crash while loading dx9.dll, 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.