The Column name you entered is already in use or Reserved. Choose another name

This error comes when you try to create new column in sharepoint.
Why this error comes?
1. column with same name is already created
2. or it is reserved.

it might be possible you create a column with name 'abc' then you delete it and again try to crate column with name 'abc' and it gives error


At such situation you can use below method:-

1. open create new column page
2. tpye
  javascript:g_FieldName={};alert('Successfully cleared forbidden columns');
in address bar.
3. hit enter

now you will be able to create column with name 'abc'