Website migration error analysis

The client moved his site (Social Engine v.4 script) from one hosting to another incorrectly. As a result a lot of errors appeared which caused troubles in work of the whole site. Our task was profound investigation of the system. We have found out that the access rights for files and folders had been set incorrectly, database user was absent and so on. So we fixed this issue and some other technical points. Now the site work is stable.