Troubleshooting: Why won't the Update button on the Mass Attribute Update dialog enable?

This applies to versions of ArcFM older than 8.3.

Symptoms:

You are able to get the Mass Attribute Update dialog open and you can change the attributes of multiple features. The attributes that you modify appear to be updated (the field name changes to blue and the value is changed). However the Update button still isn't enabled.

Solution:

Prior to 8.3, this indicates that the property "Allow NULL Values" on the shape field on this feature class is set to No. This is not supported. Change this value to Yes.

In ArcCatalog (with ArcMap closed), right-click the feature class and select ArcFM Properties Manager.
Select the Field Info tab.
Select the field that failed to update.
In the Field Properties window, change the Allow NULL Values field to Yes.
The LengthSource field should also have this property set to Yes. This field will be available only on linear features.
Click OK.