According to a Grants.gov Blog post, Grants.gov Adobe Reader DC Compatibility Issue Workaround, a recent version of Adobe Reader DC (version 2015.010.20060) is compatible with Grants.gov.
Grants.gov applicants may continue to use Adobe Reader version 9 through 11 and, now, Adobe Reader DC version 2015.010.20060 or later. Versions of Adobe Reader DC prior to version 2015.010.20060 are still incompatible with Grants.gov.
Applicants who would like to use Adobe Reader DC must download the application package from Grants.gov again and use Adobe Reader DC Version 2015.010.20060 or later. Then after installing Adobe Reader DC, uncheck the “Show online storage when saving files” option.
For more detailed instructions, see the Grants.gov Adobe Software Compatibility page.
January 25, 2016 Research Advocate: Grants.gov and Adobe Reader DC Compatibility Issue