When upgrading to Sitefinity 15.4 from an earlier version, the database schema upgrade fails during site startup.

Sitefinity cannot create the unique index idx_sf_mb_dnc_cnt_prvdr on the sf_mb_dnc_cnt_provider table because the table contains duplicate values in the (parent_secured_object_id, nme) column pair, which must be unique in Sitefinity 15.4.

The site fails to start and the database schema upgrade cannot complete.

Receiving an error when attempting to upgrade to 15.4.8629.0

The unique index idx_sf_mb_dnc_cnt_prvdr on columns (parent_secured_object_id, nme) was introduced in Sitefinity 15.4 and did not exist in earlier versions. Duplicate rows can accumulate in the sf_mb_dnc_cnt_provider table during normal operation on earlier Sitefinity versions where uniqueness on these columns was not enforced.

The duplicate entries may involve rows where the nme column is NULL and parent_secured_object_type is Telerik.Sitefinity.DynamicModules.Builder.Proxy.DynamicModuleTypeProxy.

The sf_mb_dnc_cnt_provider table contains duplicate rows on the column pair (parent_secured_object_id, nme). Sitefinity 15.4 introduces a new unique index idx_sf_mb_dnc_cnt_prvdr on these columns that did not exist in earlier versions. The database schema upgrade fails because the CREATE UNIQUE INDEX statement cannot complete while duplicate rows are present in the table.

Execute the following actions against a copy of the site database.

1. Create a backup of the database before proceeding.

2. Execute those two sql queries

--#1
UPDATE [sf_schema_vrsns]
SET meta_data_changed = 1
WHERE module_name = 'Telerik.Sitefinity.DynamicModules.Builder.Data.OpenAccessModuleBuilderDataProvider'

--#2
UPDATE [sf_module_vrsn]
SET version = '14.2.7900.0', error_msg = '' -- SET the respective pre-upgraded version
WHERE module_name = 'ModuleBuilder'

--#3
delete from [sf_mb_dnc_cnt_provider]
where parent_secured_object_type = 'Telerik.Sitefinity.DynamicModules.Builder.Proxy.DynamicModuleTypeProxy'

3. Restart the site and after startup validate if the error persists. The problem must be no more.

Progress Article(s):
An item with the same key has already been added when accessing dynamic module grid view