Permission denied during software installation

If you haven't already, you should try logging in from an Administrator's Account, if you can, and install from there.

Hope this helps 🙂

If you haven't already done it, repair the permissions of the boot volume in Disk Utility.

Back up all data.

Boot into Recovery by holding down the key combination command-R at the startup chime. Release the keys when you see a gray screen with a spinning dial.

Note: You need an always-on Ethernet or Wi-Fi connection to the Internet to use Recovery. It won’t work with USB or PPPoE modems, or with networks that require any kind of authentication other than a WPA or WPA2 Personal password.

When the OS X Utilities screen appears, follow the prompts to reinstall the OS. You don't need to erase the boot volume, and you won't need your backup unless something goes wrong. If your Mac was upgraded from an older version of OS X, you’ll need the Apple ID and password you used to upgrade, so make a note of those before you begin.

I've given you a way to do it. The age of the computer is irrelevant. You already done something that damaged the OS installation.

Disk Warrior is also irrelevant. Some other MBP owners are going to have almost any problem. Millions of others don't.

I don't have time to waste arguing, so I'm going to sign off this discussion. Good luck.

Hi ! May i know how you were able to solve the problem after you said that you were able to talk to an Apple tech support?

thanks in advance.

Val

You might want to consider starting a new discussion. Since this one is a couple of years old, less people are likely to look at it. A new post would be much more visible. You can link to this one.