If this happened after a Progress 11 upgrade do the following if you are not on FIMS version 14.62. If you are under FIMS version 14.62 it is recommended that you upgrade to the latest version which can be obtained on the downloads page on Blackbaud.com.
If you are on Progress 10, this compile error can be ignored:
1. Copy the 'Newtonsoft.Json-v9.dll' file located in 'C:\npo\found\fims\assemblies to c:\npo\dlc\bin\, then re-name the 'Newtonsoft.Json-v9.dll' to 'Newtonsoft.Json.dll'. Note, your FIMS installation may be on another drive other than C on your server. Also note, that even if you do not use DonorCentral, you will still need to do this step.
2. Re-compile FIMS by running the command in Part 7 of the Progress 11 upgrade guide.