Cannot create cache directory .. or directory is not writable. Proceeding without cache in Laravel

When you installed composer pretty sure you used $ sudo command because of that the ~/.composer folder was created by the root.

Run this to fix the issue:

$ sudo chown -R $USER $HOME/.composer

Change the group permission for the folder

sudo chown -R w3cert /home/w3cert/.composer/cache/repo/https---packagist.org

and the Files folder too

sudo chown -R w3cert /home/w3cert/.composer/cache/files/

I'm assuming w3cert is your username, if not change the 4th parameter to your username.

If the problem still persists try

sudo chown -R w3cert /home/w3cert/.composer

Now, there is a chance that you won't be able to create your app directory, if that happens do the same for your html folder or the folder you are trying to create your laravel project in.

Hope this helps.

Give full access of .composer to user.

sudo chown -R 'user-name' /home/'user-name'/.composer

or

sudo chmod 777 -R /home/'user-name'/.composer

user-name is your system user-name.

to get user-name type "whoami" in terminal: