Moving CI website to another server - only blank page showing

So I changed the driver from mysql to mysqli in database.php.
I got many error messages, when I load the page:
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May I do something to fix these errors? :/

The steps I usually take to find errors:

1. The generated log file can be deleted or renamed if you are paranoid.

2. The log file indicates how far CI progressed before reaching an error which prevents further execution.

3. Always assume the CI/system folder is not the problem and not to be modified.

4. Try to fix the first error shown in your own CI/application folder and ignore subsequent errors.

5. From the log shown:

PHP Code:

ERROR - 2018-07-04 07:50:46 --> Severity: Notice  --> Undefined variable: row /var/www/html/szig/application/views/main_view.php 12
ERROR - 2018-07-04 07:50:46 --> Severity: Notice  --> Trying to get property of non-object /var/www/html/szig/application/views/main_view.php 12 


Find and fix the above error and with a bit of luck...