So about 5 minutes into logging into my Mac, all write functions on my hard drive stop working and an error with code - 50 pops up. (See screenshot.) This includes, but is not limited to, the following Copying any file Moving any file within the drive Downloading anything Saving anything in a software Deleting a file Emptying Trash The error starts appearing about 5 minutes after start up, so I'm able to run my machine normally before that. What I've tried till now based on suggestions on other threads : Installed an anti-virus Ran a Disk Utility First Aid (Including recovery mode) Ran FSCK on single user mode Booted up in safe mode - in safe mode, everything seemed to work all right. I'm honestly frustrated of having to restart over and over again after every five minutes and have no idea what to do anymore. Since, it seemed to work fine in safe mode, I'm guessing it could be a software which starts at start up at that point, but I have no clue how to work this. All my work has been of halt for two days due to this. I'm using a Macbook Pro Mid 2012, non-retina with macOS Sierra. Any help would be appreciated.