This error can be presented if the Microsoft .NET Framework has been updated to 4.6.2 or above. The following steps can be taken to resolve the error:
  1. Access the Blackbaud NetCommunity web server
  2. Navigate to Program Files > Blackbaud > NetCommunity > admin > Events; typically this has a file path similar to: C:\Program Files\Blackbaud\NetCommunity\admin\Events
  3. Edit the file Event2PriceSummary.ascx
  4. Find line 25: ID="lblAmt" Text='<%# FormatCurrency(Decimal.Parse(Eval("GiftAmount"), Globalization.CultureInfo.InvariantCulture))%>' />
  5. Replace this line with the following: ID="lblAmt" Text='<%# FormatCurrency(Decimal.Parse(Eval("GiftAmount"), System.Globalization.CultureInfo.InvariantCulture))%>' />
  6. Save the file

If this alternative does not work to resolve the error, you will need to downgrade the .NET Framework to 4.6.1. After downgrading, you may need to revert the application pool settings in IIS. 

Please contact the appropriate software vendor or IT professional for assistance with this process or issue which is beyond Blackbaud's scope of support.