If you are using SSMS V17.4 as I am
You may encounter a weird error. This can be repeated as follows:
Open a new SSMS window, and connect to any SQL Server instance (I tested on connections to SQL Server 2012/2014/2016/2017), and then execute the following
set showplan_all on;
and then just try to execute it again, or execute any query in the same window, like
print getdate(); — or
select getdate();
You will see a popup window with the error message like the following
Input string was not in a correct format. (mscorlib)
This issue does not exist in SSMS V17.0 and certainly not in earlier version of SSMS application as well.