Upgraded to SS4 from SS3

Questions
1

Silverstripe Version: 4

Question:

To upgrade my application from SS3 to SS4, i followed the steps mention in https://docs.silverstripe.org/en/4/upgrading/ and haven’t receive any error but when i rum the application i am getting the below error:-
PHP Fatal error:Uncaught PhpParser\Error: Cannot use TextareaField as TextareaField because the name is already in use on line 2 in /Applications/MAMP/htdocs/silverstripe-project/vendor/nikic/php-parser/lib/PhpParser/NodeVisitor/NameResolver.php:155

// Include any relevant code. If you have a lot of code, link to a gist instead.
2

Getting the same error, but for “ContentController” instead. Can you remember how you resolved it?

3

Ok, in my case there seemed to be a duplicate use statement for ContentController in PageController.php.