Ssis-965 <VALIDATED>

is a defect that surfaces only in runtime , when the metadata (column names, data types, lengths, nullability) that SSIS builds at design‑time does not match the actual schema that the source delivers at execution. The error message looks like:

// Load schema JSON var schema = JArray.Parse(File.ReadAllText(schemaFile)); foreach (var col in schema) var input = source.InputCollection[0]; var colMeta = input.InputColumnCollection.New(); colMeta.Name = col["ColumnName"].ToString(); colMeta.DataType = DataType.DT_WSTR; // Map to DT_WSTR for nvarchar colMeta.Length = 4000; SSIS-965

// Configure source connection (assume connection manager already exists) var cm = pkg.Connections["FlatFileConn"]; source.RuntimeConnectionCollection[0].ConnectionManager = DtsConvert.GetExtendedInterface(cm); source.RuntimeConnectionCollection[0].ConnectionManagerID = cm.ID; is a defect that surfaces only in runtime

contains an additional column Region at the end: The fix is to force a metadata refresh

SSIS‑965 – “Data Flow task fails with The data type of the column is unknown ” TL;DR – SSIS‑965 is a long‑standing “metadata‑loss” bug that appears when a Flat File Source (or OLE DB Source ) is used together with dynamic column discovery in a Data Flow that is later reused by a Script Component or Derived Column . The root cause is the way the SSIS runtime caches the metadata of the source at design‑time but discards it at run‑time when the Connection Manager is refreshed with a new schema. The fix is to force a metadata refresh (re‑initialise the component) or, better, to decouple schema discovery from the data flow by using a staging table or Data Flow parameters . Below is a step‑by‑step forensic analysis, a reproducible test case, the official Microsoft KB work‑around, a clean‑room implementation that eliminates the issue, performance considerations, and a checklist for preventing the bug in future projects. 1. Background & Why It Matters SQL Server Integration Services (SSIS) is the ETL engine for the Microsoft data‑platform. A huge proportion of SSIS packages are data‑flow‑centric – they read from a source, perform transformations, and write to a destination.

Error 0xC0202009 at Data Flow Task, OLE DB Source [1]: The data type of column "CustomerID" is unknown. Consequences:

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