Can not install or update anything in wordpress on localhost

Can you please add more of a description of your issue:
OS?
Server config on Localhost? MAMP, XAMP, WAMP, native?
WordPress version?
Theme name?

From your question I have no ideas…

I am using :
Wordpress 4.8.2
Localhost (server) : installed PHP, Apache and SQL separately (guess its LAMP)
OS: Ubuntu 16.04
Theme: Native Church
Thanks

Sorry, please visit your theme developer’s page for support:

From Forum Guidelines

For support of commercial themes or plugins, go to the official support channel.

In order to be good stewards of the WordPress community, and encourage innovation and progress, we feel it’s important to direct people to those official locations. Doing this will provide the developer with the income they need to make WordPress awesome.

Forum volunteers are also not given access to commercial products, so they would not know why a commercial theme or plugin is not working properly.

Ultimately, the vendors are responsible for supporting their commercial product.

Thanks @jaycbrf.
I tried installing a new wordpress project on my localhost without adding any theme or plugin. Then I tried installing a plugin like jetpack and the same error keeps coming

Have you changed the permissions of the WordPress folder so that it can be written to?
sudo chown -R www-data:www-data /var/www

Yes. I instead did this:
sudo chown -R kofi:www-data /var/www

try adding this to wp-config:

/* REMOVE THIS LINE BEFORE GOING LIVE */

define('FS_METHOD', 'direct');

Thanks once more @jaycbrf. I already tried that but it did not solve the problem

PHP 7?

Yes PHP 7

I am lost –

I do not think it is because of PHP 7 because I have a friend who also has Ubuntu 16.04 and has PHP 7 installed but his WordPress works fine without any problem

Pls I will be happy if you can help me contact other WordPress experts who can help me solve this problem