"these endpoints now include annotation fields for all estimates. This will enable the estimates to be numeric and the character overrides will be stored in the corresponding annotation field. To accommodate this format change, the endpoints will change to add 'acs/' into the URI after the year. These changes are to the same format that data users are currently using to access the 2015 and 2016 ACS. The old endpoints will be removed on August 30th."
Reference: https://www.census.gov/content/dam/Census/data/developers/acs/acs-data-variables-guide.pdf
Endpoints for the 2010 to 2014 ACS Estimates dataset will be removed on August 30th, 2018, and "Eventually the rest of the available ACS products will be re-released this summer in the new format."
Update: Summary Level Naming and Hierarchical Access Changes
"these endpoints now include annotation fields for all estimates. This will enable the estimates to be numeric and the character overrides will be stored in the corresponding annotation field. To accommodate this format change, the endpoints will change to add 'acs/' into the URI after the year. These changes are to the same format that data users are currently using to access the 2015 and 2016 ACS. The old endpoints will be removed on August 30th."
Reference: https://www.census.gov/content/dam/Census/data/developers/acs/acs-data-variables-guide.pdf
Endpoints for the 2010 to 2014 ACS Estimates dataset will be removed on August 30th, 2018, and "Eventually the rest of the available ACS products will be re-released this summer in the new format."
Update: Summary Level Naming and Hierarchical Access Changes