Calling stored procedure from EF returns error The SqlParameter is already contained by another SqlParameterCollection

Question

I'm calling a SQL stored procedure in EF

var paramSortColumn = new SqlParameter("@SortColumn", SqlDbType.NVarChar, 200) { Value = SortColumn };
var paramSortOrder = new SqlParameter("@SortOrder", SqlDbType.NVarChar, 10) { Value = SortOrder };
var paramStartIndex = new SqlParameter("@StartIndex", SqlDbType.Int) { Value = filter.StartIndex - 1 };
var paramItemsPerPage = new SqlParameter("@ItemsPerPage", SqlDbType.Int) { Value = filter.ItemsPerPage };

var paramDealerBranchID = new SqlParameter("@DealerBranchIDs", SqlDbType.NVarChar){Value = selectedIds };
var paramBypassDealerBranchIDs = new SqlParameter("@BypassDealerBranchIDs", SqlDbType.TinyInt) { Value = Convert.ToInt32(filter.ByPassDealerBranchIDs) };

var result =
    _dbContext.Database.SqlQuery<DealerMappingDetailsReportModel>(
        "usp_DealerMappingDetail @DealerBranchIDs,@BypassDealerBranchIDs,@SortColumn,@SortOrder,@StartIndex,@ItemsPerPage",
        paramDealerBranchID, paramBypassDealerBranchIDs, paramSortColumn, paramSortOrder, paramStartIndex, paramItemsPerPage
     );
return result.ToList();

but it returns

The SqlParameter is already contained by another SqlParameterCollection

Answer 1

I had the same issue with a Database.SqlQuery that was calling a Stored Procedure . Many folks recommend "clearing" and/or "cloning" the Parameters collection (among other things).

However...

I noticed my SQL command-text wasn't "complete"...and found...I had forgotten to include the EXEC command in my SQL. It looks like you may have the same issue.

I CHANGED THIS:
In my methods, I usually like to hand-back Queryables, so my methods often look like below.

...notice that 'EXEC' is missing

var query = UnitOfWork.DbContext.Database.SqlQuery<DocumentStatusDataItem>("dbo.usp_ListDocumentStatusForATFDocuments @ContextFullName, @WorkflowNames",
                                        new SqlParameter("ContextFullName", context.FullName),
                                        new SqlParameter("WorkflowNames", namesXML))
                                        .AsQueryable();

TO THIS:

...notice that 'EXEC' is now there

var query = UnitOfWork.DbContext.Database.SqlQuery<DocumentStatusDataItem>("EXEC dbo.usp_ListDocumentStatusForATFDocuments @ContextFullName, @WorkflowNames",
                                        new SqlParameter("ContextFullName", context.FullName),
                                        new SqlParameter("WorkflowNames", namesXML))
                                        .AsQueryable();

Then my calls started working:
For example...calls like this suddenly started working...and I stopped getting the exception.

List<DocumentStatusDataItem> collection = query.ToList();

However, this same solution also worked for ToList() methods I have that were having the same issue.