Our NPSP version 3.210 has been pushed to sandbox orgs. Please look for this version in your org in the next few days and report any issues. 

• We fixed a bug in Gift Entry that was producing an error for a few given scenarios. See Issues Closed for more information.

#6734: NPSP Gift Entry: null input to JSON parser error  

 Push Schedule

Sandbox orgs: 2021-12-08 Production orgs: 2021-12-14