Saxon

I think this is the expected behavior.

If I'm understanding this correctly, what's happening is that run_03.bat attempts to resolve .\test.dtd with catalog_02.xml. There is no matching catalog entry for the DTD, so no match is found. The resolver reports failure and Saxon goes on to try the original URI, .\test.dtd which isn't a valid URI.

You can see this if you set -Dxml.catalog.defaultLoggerLogLevel=debug:

...
config: Fix Windows system identifiers: true
config: Default logger log level: debug
config: Searching for catalogs on classpath:
config: Catalog: jar:file:/C:/Users/norm/Desktop/%236222_xmlresolver/SaxonHE12-3J/lib/xmlresolver-5.2.0-data.jar!/org/xmlresolver/catalog.xml
config: Throw URI exceptions: true
config: Catalog list cleared
config: Catalog: file:/C:/Users/norm/Desktop/%236222_xmlresolver/catalog_02.xml
request: resolveEntity: ./test.dtd (baseURI: file:/C:/Users/norm/Desktop/%236222_xmlresolver/xml-inputfile.xml, publicId: null)
config: Loaded catalog: file:/C:/Users/norm/Desktop/%236222_xmlresolver/catalog_02.xml
config: Loaded catalog: jar:file:/C:/Users/norm/Desktop/%236222_xmlresolver/SaxonHE12-3J/lib/xmlresolver-5.2.0-data.jar!/org/xmlresolver/catalog.xml
response: resolveEntity: null
java.lang.IllegalArgumentException: Illegal character in path at index 1: .\test.dtd
        at java.base/java.net.URI.create(URI.java:883)
        at java.base/java.net.URI.resolve(URI.java:1066)

Note that the resolver is looking for ./test.dtd indicating that it has fixed the Windows system identifier.

The point at which the resolver responds null is the point at which the resolver exits the picture. At this point, Saxon has no choice but to ask for the original URI and that...isn't a URI.

XML system identifiers are not filenames, or file paths, they are URIs and "\" is not a valid character in a URI.

If you can't fix the input documents to contain valid system identifiers as URIs, then your best bet is to make sure that the catalog successfully resolves the identifiers.

Thank you.