diff --git a/ncclient/operations/util.py b/ncclient/operations/util.py
index 0d1bb38..b8512f5 100755
--- a/ncclient/operations/util.py
+++ b/ncclient/operations/util.py
@@ -50,9 +50,13 @@ def build_filter(spec, capcheck=None):
     if isinstance(spec, tuple):
         type, criteria = spec
         if type == "xpath":
-            ns, select = criteria
-            rep = new_ele_nsmap("filter", ns, type=type)
-            rep.attrib["select"] = select
+            if isinstance(criteria, tuple):
+                ns, select = criteria
+                rep = new_ele_nsmap("filter", ns, type=type)
+                rep.attrib["select"] = select
+            else:
+                rep = new_ele("filter", type=type)
+                rep.attrib["select"]=criteria
         elif type == "subtree":
             rep = new_ele("filter", type=type)
             rep.append(to_ele(criteria))

Release 0.6.8 xpath filter incompatible with previous releases
The following code used to work in 0.6.7 and earlier,

```
from ncclient import manager

path = '/a/b/c'

with manager.connect(...) as m:
    reply = m.get('xpath', path)
```
Now this code throws an error
```
  File "test-netconf.py", line 7, in <module>
    reply = m.get(filter=('xpath', path))
  File "/usr/local/lib/python3.8/site-packages/ncclient/manager.py", line 226, in execute
    return cls(self._session,
  File "/usr/local/lib/python3.8/site-packages/ncclient/operations/retrieve.py", line 83, in request
    node.append(util.build_filter(filter))
  File "/usr/local/lib/python3.8/site-packages/ncclient/operations/util.py", line 53, in build_filter
    ns, select = criteria
ValueError: too many values to unpack (expected 2)
```

The path parameter in 0.6.7 used to be a string, even the current document still so specifies. But in the unit test and the code the path is expected as a tuple.

Please consider making this backward compatible, and announce such major changes before releasing it.
diff --git a/test/unit/operations/test_utils.py b/test/unit/operations/test_utils.py
index 45adbd3..fd13fd5 100644
--- a/test/unit/operations/test_utils.py
+++ b/test/unit/operations/test_utils.py
@@ -57,7 +57,16 @@ class TestUtils(unittest.TestCase):
         call = ElementTree.tostring(reply)
         self.assertEqual(call, ElementTree.tostring(to_ele(xml)))
 
-    def test_build_filter_2(self):
+    def test_build_filter_xpath(self):
+        criteria = "configuration/system"
+        filter = ("xpath", criteria)
+        reply = build_filter(filter)
+        call = ElementTree.tostring(reply)
+        node = new_ele("filter", type="xpath")
+        node.attrib["select"] = criteria
+        self.assertEqual(call, ElementTree.tostring(node))
+
+    def test_build_filter_xpath_ns(self):
         select = "configuration/system"
         ns = {"ns0": "http://www.xxx.org"}
         criteria = (ns, select)
@@ -68,7 +77,7 @@ class TestUtils(unittest.TestCase):
         node.attrib["select"] = select
         self.assertEqual(call, ElementTree.tostring(node))
 
-    def test_build_filter_3(self):
+    def test_build_filter_subtree(self):
         criteria =  """<configuration>
             <system>
                 <services/>
@@ -81,7 +90,7 @@ class TestUtils(unittest.TestCase):
         node.append(to_ele(criteria))
         self.assertEqual(call, ElementTree.tostring(node))
 
-    def test_build_filter_4(self):
+    def test_build_filter_other(self):
         criteria =  """<configuration>
             <system>
                 <services/>

pip install -e .
parse_log_pytest
requirements.txt
pytest pytest-cov sphinx flake8 mock nose
apt-get update apt-get install -y libxml2-dev libxslt1-dev
3.7
requirements.txt
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
alabaster==0.7.13
Babel==2.14.0
bcrypt==4.2.1
certifi @ file:///croot/certifi_1671487769961/work/certifi
cffi==1.15.1
charset-normalizer==3.4.1
coverage==7.2.7
cryptography==44.0.2
docutils==0.19
exceptiongroup==1.2.2
flake8==3.9.2
idna==3.10
imagesize==1.4.1
importlib-metadata==6.7.0
iniconfig==2.0.0
Jinja2==3.1.6
lxml==5.3.1
MarkupSafe==2.1.5
mccabe==0.6.1
mock==5.2.0
-e git+https://github.com/ncclient/ncclient.git@1e767daffa8ccb6256f315433ab8db50ee48380d#egg=ncclient
nose==1.3.7
packaging==24.0
paramiko==3.5.1
pluggy==1.2.0
pycodestyle==2.7.0
pycparser==2.21
pyflakes==2.3.1
Pygments==2.17.2
PyNaCl==1.5.0
pytest==7.4.4
pytest-cov==4.1.0
pytz==2025.2
requests==2.31.0
six==1.17.0
snowballstemmer==2.2.0
Sphinx==5.3.0
sphinxcontrib-applehelp==1.0.2
sphinxcontrib-devhelp==1.0.2
sphinxcontrib-htmlhelp==2.0.0
sphinxcontrib-jsmath==1.0.1
sphinxcontrib-qthelp==1.0.3
sphinxcontrib-serializinghtml==1.1.5
tomli==2.0.1
typing_extensions==4.7.1
urllib3==2.0.7
zipp==3.15.0

name: ncclient
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - ca-certificates=2025.2.25=h06a4308_0
  - certifi=2022.12.7=py37h06a4308_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.4.4=h6a678d5_1
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=1.1.1w=h7f8727e_0
  - pip=22.3.1=py37h06a4308_0
  - python=3.7.16=h7a1cb2a_0
  - readline=8.2=h5eee18b_0
  - setuptools=65.6.3=py37h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - wheel=0.38.4=py37h06a4308_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - alabaster==0.7.13
      - babel==2.14.0
      - bcrypt==4.2.1
      - cffi==1.15.1
      - charset-normalizer==3.4.1
      - coverage==7.2.7
      - cryptography==44.0.2
      - docutils==0.19
      - exceptiongroup==1.2.2
      - flake8==3.9.2
      - idna==3.10
      - imagesize==1.4.1
      - importlib-metadata==6.7.0
      - iniconfig==2.0.0
      - jinja2==3.1.6
      - lxml==5.3.1
      - markupsafe==2.1.5
      - mccabe==0.6.1
      - mock==5.2.0
      - nose==1.3.7
      - packaging==24.0
      - paramiko==3.5.1
      - pluggy==1.2.0
      - pycodestyle==2.7.0
      - pycparser==2.21
      - pyflakes==2.3.1
      - pygments==2.17.2
      - pynacl==1.5.0
      - pytest==7.4.4
      - pytest-cov==4.1.0
      - pytz==2025.2
      - requests==2.31.0
      - six==1.17.0
      - snowballstemmer==2.2.0
      - sphinx==5.3.0
      - sphinxcontrib-applehelp==1.0.2
      - sphinxcontrib-devhelp==1.0.2
      - sphinxcontrib-htmlhelp==2.0.0
      - sphinxcontrib-jsmath==1.0.1
      - sphinxcontrib-qthelp==1.0.3
      - sphinxcontrib-serializinghtml==1.1.5
      - tomli==2.0.1
      - typing-extensions==4.7.1
      - urllib3==2.0.7
      - zipp==3.15.0
prefix: /opt/conda/envs/ncclient

test/unit/operations/test_utils.py::TestUtils::test_build_filter_xpath
test/unit/operations/test_utils.py::TestUtils::test_build_filter test/unit/operations/test_utils.py::TestUtils::test_build_filter_other test/unit/operations/test_utils.py::TestUtils::test_build_filter_subtree test/unit/operations/test_utils.py::TestUtils::test_build_filter_xpath_ns test/unit/operations/test_utils.py::TestUtils::test_datastore_url test/unit/operations/test_utils.py::TestUtils::test_datastore_url_2 test/unit/operations/test_utils.py::TestUtils::test_datastore_url_3 test/unit/operations/test_utils.py::TestUtils::test_one_of_1 test/unit/operations/test_utils.py::TestUtils::test_one_of_2 test/unit/operations/test_utils.py::TestUtils::test_one_of_3
ncclient/operations/util.py
ncclient/operations/util.py