Symptoms
After installing or upgrading to the 9.x version of the software, the following error is encountered at startup: "Could not load file or assembly 'NetgiroClient' or one of its dependencies. An attempt was made to load a program with an incorrect format."
Cause
The 3rd party assembly required by the NetGiro gateway currently does not support 64 bit environments.
Solution
Delete the NetgiroClient.dll file in the /bin folder and the site should start.