get_nwbfile_version/get_nwb_version: Fix parsing pre-semver version specifiers

CHANGELOG.md

@@ -1,5 +1,11 @@
 # PyNWB Changelog
 
+## Unreleased
+
+### Fixed
+- Fixed parsing of the nwb_version attribute which followed the previous suggestion to have a `NWB-` prefix.
+  @t-b [#2118](https://github.com/NeurodataWithoutBorders/pynwb/pull/2118)
+
 ## PyNWB 3.1.1 (July 22, 2025)
 
 ### Bug fixes

src/pynwb/__init__.py

@@ -297,7 +297,7 @@ def get_nwbfile_version(**kwargs):
         nwb_version_string = nwb_version_string.decode()
 
     # Parse the version string
-    nwb_version_parts = nwb_version_string.replace("-", ".").replace("_", ".").split(".")
+    nwb_version_parts = nwb_version_string.replace("NWB-", "").replace("-", ".").replace("_", ".").split(".")
     nwb_version = tuple([int(i) if i.isnumeric() else i
                          for i in nwb_version_parts])
     return nwb_version_string, nwb_version

src/pynwb/io/utils.py

@@ -37,6 +37,8 @@ def get_nwb_version(builder: Builder, include_prerelease=False) -> Tuple[int, ..
             return (2, 0, 0)
         else:
             return (2, 0, 0, "b")
+
+    nwb_version = nwb_version.removeprefix("NWB-")
     nwb_version_match = re.match(r"(\d+\.\d+\.\d+)", nwb_version)[0]  # trim off any non-numeric symbols at end
     version_list = [int(i) for i in nwb_version_match.split(".")]
     if include_prerelease:

tests/integration/utils/test_io_utils.py

@@ -57,6 +57,13 @@ def test_get_nwb_version_20b(self):
         assert get_nwb_version(builder1) == (2, 0, 0)
         assert get_nwb_version(builder1, include_prerelease=True) == (2, 0, 0, "b")
 
+    def test_get_nwb_version_NWB_prefix(self):
+        """Get the NWB version from a builder where version == "NWB-2.1.3"."""
+        builder1 = GroupBuilder(name="root")
+        builder1.set_attribute(name="nwb_version", value="NWB-2.1.3")
+        assert get_nwb_version(builder1) == (2, 1, 3)
+        assert get_nwb_version(builder1, include_prerelease=False) == (2, 1, 3)
+
 class TestGetNWBBackend(TestCase):
     def setUp(self):
         self.nwbfile = NWBFile(session_description='a test NWB File',