I’ve noticed many forum posts about you guys get problem with activation code already in use. And I see that many guys told that they haven’t play GTA 5 in a long or short period and then they come back but can’t play due to this problem. I’m here as a kindful guy to collect some ways of the others to help you.
#1 go into program files (not x86) and go down to the Rockstar games folder.
Next, find “PlayGTA5.exe”
When open the link it should go back to the same glitched state. DO NOT CLOSE THIS WINDOW JUST YET Instead, click the gray “back” button to go back to the login screen. This time you’ll actually see a check box that checks if you want to auto login or not. UNCHECK THIS EXACT BOX AND CLOSE THE WINDOW.
After doing this go back into steam and boot the game, it should be working perfectly now after it automatically signs you in.
#2 If you purchased the game from Steam (I found this on the rockstar support page)
Click the “PRE-LOAD” button in the Steam client (Library->Grand Theft Auto V) and begin downloading the game. Your Rockstar Activation Code will automatically be entered and used when you launch the game for the first time, so you do not need to enter it manually anywhere. Your game download will become playable on April 14, 2015. If you encounter any issues with your Steam pre-load or activation code, please contact Steam Support.
#3 Literally got that just now. I just pressed Back, re-typed my password and then the game could launch.
#4 Quit the game and re-launch it. It should work now.