Recently, I move my Umbraco 8 websites web-hosting from Azure to a cheaper alternative (you can see the reasons in this post). The first time I tried to deploy my website onto my new hosting, it failed with this error:

Umbraco Loading Error

After a lot of head-scratching, I realized it was down to permissions on my new web host. The hosting account only set read-only access for .NET by default. As Umbraco needs to write to the App_data folder on start-up this was causing the whole site to throw an error. The solution was simple enough, give .NET read/write permissions. The lazy way is to apply read/write permissions to the whole webroot. Security-wise this is sub-optimal. To be more security conscious, set 'read/write permissions on the App_Data, Config, Media and View folders. After applying for the correct permissions, my site loaded as expected. Enjoy!