0x8004D293 : Cannot update RequiredLevel of attribute CustomerId to SystemRequired

Hi All, recently I came across an issue while importing customization's from an existing environment to a new environment.

Error Details:
Entity Relationships || opportunity_customer_accounts || Failure || 0x8004D293 ||Cannot update              RequiredLevel of attribute CustomerId to SystemRequired.

 Source environment is upgraded to UP12, but the new UI not enabled on it. Target new environment by default came with UR12 new UI enabled.  Both the environments are CRM 2011 online.

During UR12, CustomerId field requirement level has been changed from System Required to Business Required. But CustomerId field on the opportunity is an OOB lookup field and we can't modify the requirement level.

 Its a known issue & documented  at http://msdn.microsoft.com/en-us/library/gg309589.aspx

Solution:

1. Enabling new UI in the Source environment. During new UI enable process, CustomerId field requirement level auto upgraded to Business required.

   Follow the following step to upgrade CRM to new UI.

    Settings => Administration => Product Updates

 Updated UX forms avaiable only for Leads, Contacts, Accounts, Opportunities and Cases. New UI does not support java script and it has other limitations.
However you have an option to Turn on / off  the new sales and service process forms
http://rc.crm.dynamics.com/rc/2011/en-us/online/5.1_OSDP/help/source_sf_turn_on_sales_forms.htm

Hope it helps!!!