Why is there a column of whitespace that spans the entire page?

Issue:

Managed code has been changed but when you view your changes, the layout is not what it should be.

Solution:

This issue can be caused by an unclosed quotation within an html string in a control as shown below. It will be found in the managed code of the controls that are on the column highlighted in red above.

Example Code:

Code before fix:

Code after fix: