diff --git a/docs/changelog/1042.bugfix.rst b/docs/changelog/1042.bugfix.rst
new file mode 100644
index 00000000..250208f3
--- /dev/null
+++ b/docs/changelog/1042.bugfix.rst
@@ -0,0 +1,1 @@
+fix regression with ``3.5.0``: specifying ``--installpkg`` raises ``AttributeError: 'str' object has no attribute 'basename'``
diff --git a/src/tox/package.py b/src/tox/package.py
index bbd191fd..29548c65 100644
--- a/src/tox/package.py
+++ b/src/tox/package.py
@@ -108,9 +108,9 @@ def get_local_package(config, report, session):
     path = config.option.installpkg
     if not path:
         path = config.sdistsrc
-    path = session._resolve_package(path)
-    report.info("using package {!r}, skipping 'sdist' activity ".format(str(path)))
-    return path
+    py_path = py.path.local(session._resolve_package(path))
+    report.info("using package {!r}, skipping 'sdist' activity ".format(str(py_path)))
+    return py_path
 
 
 def build_package(config, report, session):

Testing with `--installpkg somewheel.whl` broken (Regression in 3.5.0)
Tox 3.5.0 seems to break my Travis tests for Prequ. I have set the Travis configuration so that it runs `python setup.py bdist_wheel` and then runs as `tox -v --installpkg dist/*.whl`.  This worked fine with earlier Tox versions (<=3.4.0).

With Tox 3.5.0 my Travis job started to break with an exception raised from this line:

https://github.com/tox-dev/tox/blob/5f2535f1a697fe4bfbec571407a742615b410e24/src/tox/package.py#L64

The exception was `AttributeError: 'str' object has no attribute 'basename'`.  Full trace back is available in the build log: https://travis-ci.org/suutari/prequ/jobs/438550460

I think the error happens because `acquire_package` returns a bare `str` if `--instalpkg` is used, but otherwise it seems to return a `_path.local.LocalPath` instance. The failing code in `create_session_view` seems to assume (since commit 6538f74fd7) that the `package` is a a rich `Path` object rather than bare string.
diff --git a/tests/unit/test_package.py b/tests/unit/test_package.py
index d46d229d..e4c39a48 100644
--- a/tests/unit/test_package.py
+++ b/tests/unit/test_package.py
@@ -389,3 +389,18 @@ def test_tox_parallel_build_safe(initproj, cmd, mock_venv, monkeypatch):
     assert len(dist_after) == 1
     sdist = dist_after[0]
     assert t1_package != sdist
+
+
+def test_install_via_installpkg(mock_venv, initproj, cmd):
+    base = initproj(
+        "pkg-0.1",
+        filedefs={
+            "tox.ini": """
+                [tox]
+                install_cmd = python -m -c 'print("ok")' -- {opts} {packages}'
+                """
+        },
+    )
+    fake_package = base.ensure(".tox", "dist", "pkg123-0.1.zip")
+    result = cmd("-e", "py", "--notest", "--installpkg", str(fake_package.relto(base)))
+    assert result.ret == 0, result.out

pip install -e .[dev]
parse_log_pytest
requirements.txt
pytest pytest-cov pytest-mock pytest-xdist
3.6
requirements/base.txt
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
attrs==22.2.0
certifi==2021.5.30
coverage==6.2
distlib==0.3.9
execnet==1.9.0
filelock==3.4.1
importlib-metadata==4.8.3
importlib-resources==5.4.0
iniconfig==1.1.1
packaging==21.3
platformdirs==2.4.0
pluggy==0.13.1
py==1.11.0
pyparsing==3.1.4
pytest==7.0.1
pytest-cov==4.0.0
pytest-mock==3.6.1
pytest-xdist==3.0.2
six==1.17.0
toml==0.10.2
tomli==1.2.3
-e git+https://github.com/tox-dev/tox.git@6f8a1f0a31bb126840c28b46f35be3b2ab61b9b7#egg=tox
typing_extensions==4.1.1
virtualenv==20.17.1
zipp==3.6.0

name: tox
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=2021.5.30=py36h06a4308_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.3=he6710b0_2
  - 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=21.2.2=py36h06a4308_0
  - python=3.6.13=h12debd9_1
  - readline=8.2=h5eee18b_0
  - setuptools=58.0.4=py36h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - wheel=0.37.1=pyhd3eb1b0_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - attrs==22.2.0
      - coverage==6.2
      - distlib==0.3.9
      - execnet==1.9.0
      - filelock==3.4.1
      - importlib-metadata==4.8.3
      - importlib-resources==5.4.0
      - iniconfig==1.1.1
      - packaging==21.3
      - platformdirs==2.4.0
      - pluggy==0.13.1
      - py==1.11.0
      - pyparsing==3.1.4
      - pytest==7.0.1
      - pytest-cov==4.0.0
      - pytest-mock==3.6.1
      - pytest-xdist==3.0.2
      - six==1.17.0
      - toml==0.10.2
      - tomli==1.2.3
      - typing-extensions==4.1.1
      - virtualenv==20.17.1
      - zipp==3.6.0
prefix: /opt/conda/envs/tox

tests/unit/test_package.py::test_install_via_installpkg
tests/unit/test_package.py::test_package_isolated_toml_no_build_system tests/unit/test_package.py::test_package_isolated_toml_no_requires tests/unit/test_package.py::test_package_isolated_toml_no_backend tests/unit/test_package.py::test_package_isolated_toml_bad_requires tests/unit/test_package.py::test_package_isolated_toml_bad_backend
tests/unit/test_package.py::test_make_sdist tests/unit/test_package.py::test_make_sdist_distshare tests/unit/test_package.py::test_sdistonly tests/unit/test_package.py::test_separate_sdist_no_sdistfile tests/unit/test_package.py::test_separate_sdist tests/unit/test_package.py::test_sdist_latest tests/unit/test_package.py::test_installpkg tests/unit/test_package.py::test_package_isolated_no_pyproject_toml tests/unit/test_package.py::test_dist_exists_version_change tests/unit/test_package.py::test_tox_parallel_build_safe
docs/changelog/1042.bugfix.rst src/tox/package.py
docs/changelog/1042.bugfix.rst src/tox/package.py