Fedex Service Integration Error (unable to generate a temporary class)

This might be an issue with the way that WSDL.exe generates the client code.

You will have to manually edit Reference.cs file to replace double brackets [][] to single [] in EmailNotificationEventType definition.

From Microsoft:

There is no resolution available at this point. However, three workarounds are available:

• You can generate the proxy class manually by using WSDL.exe and then change the proxy class in which the data type was inappropriately created as a two-dimensional array (for example, "CustomType[][]") so that it is a single-dimensional array (for example, "CustomType[]").
• You can change the data type in the desired Web Services Description Language (WSDL) so that a second, optional element is included in the definition. You can do this by adding an element such as the following: <xs:element minOccurs="0" name="dummyElement" nillable="true" type="xs:string"/>
• You can change the complex type in the desired WSDL so that the boundary attributes are part of the complex type instead of being part of the element. (That is, you can move the minOccurs and maxOccurs attributes to the complex type and then remove them from the element.)

Check also this link for further explanation.

I tried the third option "You can change the complex type in the desired WSDL so that the boundary attributes are part of the complex type instead of being part of the element. (That is, you can move the minOccurs and maxOccurs attributes to the complex type and then remove them from the element.)" and it worked. The solution below:

Removed from the WSDL the minOccurs and maxOccurs for the NotificationEventsAvailable element [see the image below]