What does Windows error code 14066 (ERROR_SXS_XML_E_RESERVEDNAMESPACE) mean?

ERROR_SXS_XML_E_RESERVEDNAMESPACE

ERROR_SXS_XML_E_RESERVEDNAMESPACE (0x000036F2) is a Windows Side-by-Side XML parser status for application, assembly, policy, or configuration manifest processing.

XML namespace processing reserves the xml and xmlns mechanisms, and names beginning with the letters XML in any case combination are reserved for standardization. Application-defined prefixes must not appropriate that reserved family.

XML rule involved

Namespaces in XML binds the xml prefix to the standard XML namespace and uses xmlns only for namespace declarations. A custom manifest namespace should use a different prefix and bind it to its own namespace name.

What to inspect

• Find the prefix at the parser location and determine whether it begins with a reserved XML case variant.
• Rename a custom prefix consistently on both the xmlns:prefix declaration and every qualified name that uses it.
• Do not redefine the standard xml or xmlns prefixes to point at application-specific namespace URIs.

Use sxstrace to locate the manifest containing the namespace declaration; the correction belongs in that manifest producer, not in WinSxS assembly version policy.

References

• Microsoft: System Error Codes 12000-15999
• Microsoft: Side-by-Side manifest files reference
• Microsoft: sxstrace
• W3C: Namespaces in XML 1.0