Error when upgrading to 4.4.1

There are times when you will have to change permissions to upload as in this case caching. Once it is enabled change back your files to their original permissions.You are correct don’t leave files permanently with chmod 777.
It is quite possible that your host has nailed down the files for security, which unfortunately because of some unsavoury characters is warranted.

After doing a lot of research just find the solution for this.There is a malware in my wp-config file and one another file due to which my host provider i.e. hostgator blocked my port 80/443 due to which I am unable to upload any plugin/theme. After removing the malware I have made a request to unblock port and after some time my port become open and issue is resolved.

For hostgator you can check the port :-
In cPanel – Health checks and monitoring – Port 80 option.

Also , note that the files you are deleting if they are important for your website to run , make sure to re upload them.

I hope it will help other peoples facing same issue ??

@kapilkapoor I am having this issue with a new site. Most likely this is the problem.

How did you knew you had malware on your wp-config file?

Did you contact your service provider (i.e. Hostgator) by phone or mail?

In Cpanel we can check this by :-

In cPanel – Health checks and monitoring – Port 80 option.

You can check snapshot https://awesomescreenshot.com/0e25kz5f47
And yes if you can contact to your hosting they can also check for this.
This is the live chat link for hostgator :- https://chat.hostgator.com/