Rocket Theme Admin Error (E_WARNING)

Grav Error:

Whoops \ Exception \ ErrorException (E_WARNING)
Unknown: open(/home/content/86/4795186/tmp/sess_t3tjo8rujpc7tgccko2bujaod3, O_RDWR) failed: No such file or directory (2)

RocketTheme File Causing The Error?
/home/content/86/4795186/html/godaddy-subdirectory/grav-admin/vendor/rockettheme/toolbox/Session/src/Session.php

How do I fix this?

*NOTE: Grav will be hosted on GoDaddy in a subdirectory.

I'm trying to avoid WP as much as possible... tired of the whack-a-hacker game!

I have tried creating the missing /tmp/ directory, but the fix was unsuccessful thus far. Any Ideas?

Do I need to switch to another flat file CMS for support?

I even did a test w/ Just the Grav Core vs Grav core + Admin plugin:
Both admins were broken, wanting the RocketTheme.

Any Ideas?

I think, like me, a few people would love to help you get Grav up and running but are confused by your question. Could you provide more information about what you set up leading up to this point? It's a fantastic and supportive community here, but we get a little tired of having to second guess the nature of problems.

You have provided some detail I see, and I was hoping this would be clearer to others if not me.

Thanks for the first response. Does this help?
I have tired fixing it myself, but none were successful.

/home
/content
/86
/4795186
/html
/godaddy-subdirectory
/grav
/vendor
/rockettheme
/toolbox
/Session
/src
/Session.php

            throw new \RuntimeException("Session hasn't been initialized.", 500);
        }

        return self::$instance;
    }

    /**
     * Starts the session storage
     *
     * @return $this
     * @throws \RuntimeException
     */
    public function start()
    {
        // Protection against invalid session cookie names throwing exception: http://php.net/manual/en/function.session-id.php#116836
        if (isset($_COOKIE[session_name()]) && !preg_match('/^[-,a-zA-Z0-9]{1,128}$/', $_COOKIE[session_name()])) {
            unset($_COOKIE[session_name()]);
        }

        if (!session_start()) {
            throw new \RuntimeException('Failed to start session.', 500);
        }

        $this->started = true;

        return $this;
    }

    /**
     * Get session ID
     *
     * @return string Session ID
     */
    public function getId()
    {
        return session_id();
    }

    /**
     * Set session Id

Arguments

"session_start(): open(/home/content/86/4795186/tmp/sess_dmam3e3u68ej2s5l8trpai1ht5, O_RDWR) failed: No such file or directory (2)"

Have to admit, I'm still very confused. I hope someone else can follow. Your folder hierarchy looks very flat and strange to me. Did it format correctly?

Found the problem with GoDaddy… “Legacy Hosting” w/ outdated php version. Grav CMS is now working since everything was updated… (*Need to add PHP Zip Support under [Select PHP version] in cPanel).