diff --git a/lib/galaxy/config/__init__.py b/lib/galaxy/config/__init__.py
index 1dc273bc7240..ef284bae1158 100644
--- a/lib/galaxy/config/__init__.py
+++ b/lib/galaxy/config/__init__.py
@@ -512,10 +512,10 @@ def resolve(key):
             if not parent:  # base case: nothing else needs resolving
                 return path
             parent_path = resolve(parent)  # recursively resolve parent path
-            if path is not None:
+            if path:
                 path = os.path.join(parent_path, path)  # resolve path
             else:
-                path = parent_path  # or use parent path
+                log.warning("Trying to resolve path for the '%s' option but it's empty/None", key)
 
             setattr(self, key, path)  # update property
             _cache[key] = path  # cache it!
@@ -539,7 +539,7 @@ def resolve(key):
             if self.is_set(key) and self.paths_to_check_against_root and key in self.paths_to_check_against_root:
                 self._check_against_root(key)
 
-    def _check_against_root(self, key):
+    def _check_against_root(self, key: str):
         def get_path(current_path, initial_path):
             # if path does not exist and was set as relative:
             if not self._path_exists(current_path) and not os.path.isabs(initial_path):
@@ -558,6 +558,8 @@ def get_path(current_path, initial_path):
             return current_path
 
         current_value = getattr(self, key)  # resolved path or list of resolved paths
+        if not current_value:
+            return
         if isinstance(current_value, list):
             initial_paths = listify(self._raw_config[key], do_strip=True)  # initial unresolved paths
             updated_paths = []
diff --git a/lib/galaxy/jobs/__init__.py b/lib/galaxy/jobs/__init__.py
index c26aa11dbc0a..ddfb5f01102f 100644
--- a/lib/galaxy/jobs/__init__.py
+++ b/lib/galaxy/jobs/__init__.py
@@ -387,6 +387,8 @@ def __init__(self, app: MinimalManagerApp):
                             f" release of Galaxy. Please convert to YAML at {self.app.config.job_config_file} or"
                             f" explicitly set `job_config_file` to {job_config_file} to remove this message"
                         )
+                if not job_config_file:
+                    raise OSError()
                 if ".xml" in job_config_file:
                     tree = load(job_config_file)
                     job_config_dict = self.__parse_job_conf_xml(tree)
diff --git a/lib/galaxy/tool_util/linters/datatypes.py b/lib/galaxy/tool_util/linters/datatypes.py
index 534868ed01ec..f05ae5c7ab23 100644
--- a/lib/galaxy/tool_util/linters/datatypes.py
+++ b/lib/galaxy/tool_util/linters/datatypes.py
@@ -2,6 +2,7 @@
 from typing import (
     Set,
     TYPE_CHECKING,
+    Union,
 )
 
 # from galaxy import config
@@ -10,15 +11,17 @@
     listify,
     parse_xml,
 )
+from galaxy.util.resources import resource_path
 
 if TYPE_CHECKING:
     from galaxy.tool_util.lint import LintContext
     from galaxy.tool_util.parser import ToolSource
+    from galaxy.util.resources import Traversable
 
-DATATYPES_CONF = os.path.join(os.path.dirname(__file__), "datatypes_conf.xml.sample")
+DATATYPES_CONF = resource_path(__package__, "datatypes_conf.xml.sample")
 
 
-def _parse_datatypes(datatype_conf_path: str) -> Set[str]:
+def _parse_datatypes(datatype_conf_path: Union[str, "Traversable"]) -> Set[str]:
     datatypes = set()
     tree = parse_xml(datatype_conf_path)
     root = tree.getroot()
diff --git a/lib/galaxy/util/__init__.py b/lib/galaxy/util/__init__.py
index 7445a06bb3aa..7a0690412c71 100644
--- a/lib/galaxy/util/__init__.py
+++ b/lib/galaxy/util/__init__.py
@@ -45,6 +45,7 @@
     Optional,
     overload,
     Tuple,
+    TYPE_CHECKING,
     TypeVar,
     Union,
 )
@@ -75,6 +76,7 @@
 LXML_AVAILABLE = True
 try:
     from lxml import etree
+    from lxml.etree import DocumentInvalid
 
     # lxml.etree.Element is a function that returns a new instance of the
     # lxml.etree._Element class. This class doesn't have a proper __init__()
@@ -123,6 +125,10 @@ def XML(text: Union[str, bytes]) -> Element:
         XML,
     )
 
+    class DocumentInvalid(Exception):  # type: ignore[no-redef]
+        pass
+
+
 from . import requests
 from .custom_logging import get_logger
 from .inflection import Inflector
@@ -142,6 +148,9 @@ def shlex_join(split_command):
         return " ".join(map(shlex.quote, split_command))
 
 
+if TYPE_CHECKING:
+    from galaxy.util.resources import Traversable
+
 inflector = Inflector()
 
 log = get_logger(__name__)
@@ -333,7 +342,10 @@ def unique_id(KEY_SIZE=128):
 
 
 def parse_xml(
-    fname: StrPath, strip_whitespace=True, remove_comments=True, schemafname: Union[StrPath, None] = None
+    fname: Union[StrPath, "Traversable"],
+    strip_whitespace: bool = True,
+    remove_comments: bool = True,
+    schemafname: Union[StrPath, None] = None,
 ) -> ElementTree:
     """Returns a parsed xml tree"""
     parser = None
@@ -348,8 +360,10 @@ def parse_xml(
             schema_root = etree.XML(schema_file.read())
             schema = etree.XMLSchema(schema_root)
 
+    source = Path(fname) if isinstance(fname, (str, os.PathLike)) else fname
     try:
-        tree = cast(ElementTree, etree.parse(str(fname), parser=parser))
+        with source.open("rb") as f:
+            tree = cast(ElementTree, etree.parse(f, parser=parser))
         root = tree.getroot()
         if strip_whitespace:
             for elem in root.iter("*"):
@@ -359,15 +373,10 @@ def parse_xml(
                     elem.tail = elem.tail.strip()
         if schema:
             schema.assertValid(tree)
-    except OSError as e:
-        if e.errno is None and not os.path.exists(fname):  # type: ignore[unreachable]
-            # lxml doesn't set errno
-            e.errno = errno.ENOENT  # type: ignore[unreachable]
-        raise
     except etree.ParseError:
         log.exception("Error parsing file %s", fname)
         raise
-    except etree.DocumentInvalid:
+    except DocumentInvalid:
         log.exception("Validation of file %s failed", fname)
         raise
     return tree
diff --git a/test/unit/config/test_path_graph.py b/test/unit/config/test_path_graph.py
index 02f33787081f..77afe7333c55 100644
--- a/test/unit/config/test_path_graph.py
+++ b/test/unit/config/test_path_graph.py
@@ -142,7 +142,7 @@ def test_resolves_to_invalid_type(monkeypatch):
 
 
 def test_resolves_with_empty_component(monkeypatch):
-    # A path can be None (root path is never None; may be asigned elsewhere)
+    # A path can be None (root path is never None; may be assigned elsewhere)
     mock_schema = {
         "path0": {
             "type": "str",
@@ -155,7 +155,7 @@ def test_resolves_with_empty_component(monkeypatch):
         "path2": {
             "type": "str",
             "default": "value2",
-            "path_resolves_to": "path1",
+            "path_resolves_to": "path0",
         },
     }
     monkeypatch.setattr(AppSchema, "_read_schema", lambda a, b: get_schema(mock_schema))
@@ -163,5 +163,5 @@ def test_resolves_with_empty_component(monkeypatch):
 
     config = BaseAppConfiguration()
     assert config.path0 == "value0"
-    assert config.path1 == "value0"
+    assert config.path1 is None
     assert config.path2 == "value0/value2"
diff --git a/test/unit/config/test_path_resolves_to.py b/test/unit/config/test_path_resolves_to.py
index 97953b3d0787..d7e7dd0918d6 100644
--- a/test/unit/config/test_path_resolves_to.py
+++ b/test/unit/config/test_path_resolves_to.py
@@ -132,21 +132,21 @@ def test_kwargs_relative_path_old_prefix_for_other_option(mock_init):
 
 def test_kwargs_relative_path_old_prefix_empty_after_strip(mock_init):
     # Expect: use value from kwargs, strip old prefix, then resolve
-    new_path1 = "old-config"
+    new_path1 = "old-config/foo"
     config = BaseAppConfiguration(path1=new_path1)
 
-    assert config.path1 == "my-config/"  # stripped of old prefix, then resolved
+    assert config.path1 == "my-config/foo"  # stripped of old prefix, then resolved
     assert config.path2 == "my-data/my-data-files"  # stripped of old prefix, then resolved
     assert config.path3 == "my-other-files"  # no change
 
 
 def test_kwargs_set_to_null(mock_init):
-    # Expected: allow overriding with null, then resolve
+    # Expected: allow overriding with null
     # This is not a common scenario, but it does happen: one example is
     # `job_config` set to `None` when testing
     config = BaseAppConfiguration(path1=None)
 
-    assert config.path1 == "my-config"  # resolved
+    assert config.path1 is None
     assert config.path2 == "my-data/my-data-files"  # resolved
     assert config.path3 == "my-other-files"  # no change