Saxon

Following is one of the error we are getting with 11.4 version:

In template rule with match="/" of Int-1.9-TrustActivePayloadBuilderFacade.xsl
Error at char 0 in expression in xsl:variable/@select on line 8 column 68 of Int-CommonFacadeParameters.xsl:
  XPDY0002  The context item for axis step root/descendant::*:REQUEST_HEADER is absent
at variable vv:gg1775669412 on line 40 column 0 of Int-CommonFacadeParameters.xsl:
     invoked by optimizer-generated global variable select="fn:string-join(...)" at file:/tmp/dev/projects/interfaces-service/interfaces-transformer/target/test-classes/UnitTestFacade/facade/Int-CommonFacadeParameters.xsl#40
at template RequestType on line 39 column 37 of Int-CommonFacadeParameters.xsl:

Here is another one:

XPDY0002  The context item for axis step root/descendant::*:MESSAGE is absent
at template mainTemplate on line 20 column 36 of Int-1.9-TrustActivePayloadBuilder.xsl:
     invoked by xsl:call-template
  In template rule with match="/" of Int-1.9-TrustActivePayloadBuilderFacade.xsl

When you say "9.x", that covers everything from 9.0 released in 2008 to 9.9 released in 2020, and there was a great deal of change over that time. There are very detailed change logs in the user documentation, but probably far more information than you can wade through. Rather than working out what has changed, it would be best to look at your actual code and see why it is failing. To help you with that, we'll need to look at the code.

Are you running from the command line or from an API, and if so, which API?

What might be happening here is that XSLT 3.0 (and therefore Saxon) introduced the separation between the "global context item" and the "initial match selection". If you run from the command line, the -s option sets both, but on the Xslt30Transformer API they can be set independently of each other. But I'm making wild guesses here because you haven't shown us any code.