Is your feature request related to a problem? Please describe.
There is a known limitation in ACS data that can trip-up data users. ACS 1-year data is only available for places with populations of 65,000 and more people. Therefore if a user or the MCP client asks for a location with less people than that for ACS 1-year data, it doesn't exist and the API returns a 400 error. That's one of the reasons that data.census.gov has a disclaimer about missing data for your geography (see screenshot below) in the ACS 1-year tables.
Describe the solution you'd like
Return a descriptive error if a user requests ACS 1-year data for a place with less than 65,000 people, something like "This data is not available for place with population less than 65,000 people. Consider using ACS 5-year data."
Describe alternatives you've considered
An option could be to just leave the default behavior (returning 400 error).
Additional context

More info here in choosing when to use 1-year versus 5-year: https://www.census.gov/programs-surveys/acs/guidance/estimates.html
Is your feature request related to a problem? Please describe.
There is a known limitation in ACS data that can trip-up data users. ACS 1-year data is only available for places with populations of 65,000 and more people. Therefore if a user or the MCP client asks for a location with less people than that for ACS 1-year data, it doesn't exist and the API returns a 400 error. That's one of the reasons that data.census.gov has a disclaimer about missing data for your geography (see screenshot below) in the ACS 1-year tables.
Describe the solution you'd like
Return a descriptive error if a user requests ACS 1-year data for a place with less than 65,000 people, something like "This data is not available for place with population less than 65,000 people. Consider using ACS 5-year data."
Describe alternatives you've considered
An option could be to just leave the default behavior (returning 400 error).
Additional context
More info here in choosing when to use 1-year versus 5-year: https://www.census.gov/programs-surveys/acs/guidance/estimates.html