That is NOT an ERROR. It is a NOTE. You still not NOT include the CONTEXT needed to make complete sense of the NOTE. You did not show the part of the LOG that shows the CODE being run so we don't know what statement was on line 16 and column 15.
But assuming the issue is with converting BIRTHDATE to a number the value of BIRTHDATE displayed in the log is helpful. It is showing the it is empty, so that is definitely does not represent a valid date.
You can prevent that note in two ways.
You could first test if BIRTHDATE is empty and only execute the INPUT() function when it is not.
if not missing(birthdate) then birthdate_num=input(birthdate,mmddyy10.);
Or you could suppress ALL of the notes about invalid values by including the ?? modifier before the informat. Then even if the value of BIRTHDATE is 'dawn of time' you won't get an invalid value NOTE.
birthdate_num=input(birthdate,??mmddyy10.)
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