Always secure your progress before modifying core game files. Navigate to the default save directory and copy the contents to an external folder:
Once v1.5.89 is successfully installed on PC, the game may need to recompile its shaders upon the first boot. Let this process complete fully on the main menu before jumping into your save file. Skipping or interrupting shader compilation can result in massive frame drops and graphical artifacts. Optimize Your Game Post-Update horizon zero dawn remastered update v1589 install