If you have previously used variables in prior year releases, check the ACS product changes webpage for source table changes. If the variable you have been using comes from a table that has changed from the prior year, check the variables list (variables.html) and compare the variable concept and label to be sure you are requesting the correct estimate. For information on these changes, visit:
The 2016 5-Year dataset is available in a new format. For updates the U.S. Census Bureau made in June 2017, please see the following announcement describing this change. Over time, the remainder of prior year data will also be converted into this new format.