Electronic Interface No Longer working 2023.2

Trying to process payments and the electronic interface for ach payments is giving this error:CS1069:

The type name ‘ConfigurationManager’ could not be found in the namespace ‘System.Configuration’. This type has been forwarded to assembly ‘System.Configuration.ConfigurationManager, Version=0.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51’ Consider adding a reference to that assembly

Any idea on how to fix this? I found the file and see the reference is:

string asmPath = (System.Configuration.ConfigurationManager.AppSettings[“AssemblyFileSystem”] ?? “”)
.Split(new { ‘;’ }, StringSplitOptions.RemoveEmptyEntries);
Thanks!

I searched the site for ConfigurationManager and found this thread.