Ssis-776 May 2026

SSIS‑776 – A Deep Dive into the “Package Fails on Large XML Sources” Bug

Affiliations:

¹ Department of Computer Science, University A ² Department of Information Systems, University B ³ Research Lab, Company C

Quick Code Example (C# Script Component)

• The exception originates from System.Xml.XmlTextReaderImpl, which is the low‑level parser used by the XML Source.
• The line/position numbers are always 0, which indicates the parser never got far enough to produce a proper location – typical of a buffer overflow rather than a malformed file.
• The stack shows the failure occurring during PreValidate, before any rows have been emitted, which matches the “crash after 80 % of the file has been read” pattern (the validation step builds a schema cache for the entire file).