harness-library.dll is considered a type of Dynamic Link Library (DLL) file. Dynamic Link Library files, like harness-library.dll, 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. MySQL Database Server) could share the same harness-library.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 harness-library.dll is attempted to be loaded either when MySQL Database Server is starting up, or in some cases already running. Some of the most common harness-library.dll errors include:
- Access Violation at address - harness-library.dll.
- harness-library.dll could not be found.
- Cannot find C:\Program Files\MySQL\MySQL Server 8.0\bin\harness-library.dll.
- Cannot register harness-library.dll.
- Cannot start MySQL Database Server. A required component is missing: harness-library.dll. Please install MySQL Database Server again.
- Failed to load harness-library.dll.
- The application has failed to start because harness-library.dll was not found.
- The file harness-library.dll is missing or corrupt.
- This application failed to start because harness-library.dll was not found. Re-installing the application may fix this problem.
Your harness-library.dll file could be missing due to accidental deletion, uninstalled as a shared file of another program (shared with MySQL Database Server), or deleted by a malware infection. Furthermore, harness-library.dll file corruption could be caused from a power outage when loading MySQL Database Server, system crash while loading harness-library.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.