Cause

Throwing the same exception as passed to the ‘catch’ block lose the original stack trace and will make debugging this exception a lot more difficult.
The correct way to rethrow an exception without changing it is by using ‘throw’ without any parameter.

Example

try { }
catch (System.Exception ex)
{
    throw ex;
}

Code fix

You will have two choices: you can rethrow the original exception as is:

try { }
catch (System.Exception ex)
{
    throw;
}

Or you can rethrow the original exception as an inner exception, like so:

try { }
catch (System.Exception ex)
{
    throw new Exception("some reason to rethrow", ex);
}

Related rules

None

See also

TBD