A rare issue among some players is a client crash followed by the error message “Assertion failed”. These errors typically have different causes with corresponding fixes. To identify the cause please review the message and check for what file is referenced.
If the file referenced is Patchthread.cpp then save an updated Localconfig file. Make sure to replace the existing file.
If the file referenced is DTXUIStripped.cpp then your PC may not have hardware that meets the minimum requirements. Please check here for detailed requirements.
If the file referenced is MemoryManager.cpp then your system is running low on memory while running the game. In such a case please check to make sure you are running a 64-bit operating system.