Laravel chmod(/var/dev/project/storage/oauth-public.key): Operation failed: Operation not permitted

After I updated the following packages I got an error that the oauth-public.key file couldn't be found.

Package operations: 1 install, 2 updates, 0 removals

Updating laravel/framework (v5.4.27 => v5.4.28): Downloading (100%)
Installing defuse/php-encryption (v2.1.0): Downloading (100%)
Updating league/oauth2-server (5.1.3 => 5.1.4): Downloading (100%)

Firstly I deleted the two oauth- files in project/storage and then executed this command: php artisan passport:install to generate new oauth- files.

Now I get the following error when trying to access an api route.

(1/1) ErrorException chmod(/var/dev-ilario/dpi/storage/oauth-public.key): Operation failed: Operation not permitted

Stack trace

in CryptKey.php (line 51)

at HandleExceptions->handleError(2, 'chmod(/var/dev-ilario/dpi/storage/oauth-public.key): Operation failed: Operation not permitted', '/var/dev-ilario/dpi/vendor/league/oauth2-server/src/CryptKey.php', 51, array('keyPath' => 'file:///var/dev-ilario/dpi/storage/oauth-public.key', 'passPhrase' => null, 'keyPathPerms' => '644'))

via Chebli Mohamed