DLL load failed while importing: An Application Control policy has blocked this file

[sarthak127bangar@…]

The following bug report has been submitted:
Platform:        Windows-10-10.0.26200
ChimeraX Version: 1.12rc202606082314 (2026-06-08 23:14:43 UTC)
Description
pdb files not open

Log:
UCSF ChimeraX version: 1.12rc202606082314 (2026-06-08)  
© 2016-2026 Regents of the University of California. All rights reserved.  
How to cite UCSF ChimeraX  

> open C:/Users/ADMIN/Downloads/5V5Z.pdb

Traceback (most recent call last):  
File "C:\Program Files\ChimeraX 1.12rc202606082314\bin\Lib\site-
packages\chimerax\core\toolshed\info.py", line 501, in get_module  
m = importlib.import_module(self.package_name)  
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  
File "C:\Program Files\ChimeraX
1.12rc202606082314\bin\Lib\importlib\\__init__.py", line 126, in import_module  
return _bootstrap._gcd_import(name[level:], package, level)  
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  
File "<frozen importlib._bootstrap>", line 1204, in _gcd_import  
File "<frozen importlib._bootstrap>", line 1176, in _find_and_load  
File "<frozen importlib._bootstrap>", line 1147, in _find_and_load_unlocked  
File "<frozen importlib._bootstrap>", line 690, in _load_unlocked  
File "<frozen importlib._bootstrap_external>", line 940, in exec_module  
File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed  
File "C:\Program Files\ChimeraX 1.12rc202606082314\bin\Lib\site-
packages\chimerax\pdb\\__init__.py", line 29, in <module>  
from ._pdbio import standard_polymeric_res_names # this also gets shared lib
loaded  
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  
ImportError: DLL load failed while importing _pdbio: An Application Control
policy has blocked this file.  
  
During handling of the above exception, another exception occurred:  
  
Traceback (most recent call last):  
File "C:\Program Files\ChimeraX 1.12rc202606082314\bin\Lib\site-
packages\chimerax\open_command\dialog.py", line 355, in _qt_safe  
run(session, "open " + " ".join([FileNameArg.unparse(p) for p in paths]) + (""  
File "C:\Program Files\ChimeraX 1.12rc202606082314\bin\Lib\site-
packages\chimerax\core\commands\run.py", line 49, in run  
results = command.run(text, log=log, return_json=return_json)  
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  
File "C:\Program Files\ChimeraX 1.12rc202606082314\bin\Lib\site-
packages\chimerax\core\commands\cli.py", line 3245, in run  
result = ci.function(session, **kw_args)  
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  
File "C:\Program Files\ChimeraX 1.12rc202606082314\bin\Lib\site-
packages\chimerax\open_command\cmd.py", line 99, in cmd_open  
provider_args = mgr.open_args(data_format)  
^^^^^^^^^^^^^^^^^^^^^^^^^^  
File "C:\Program Files\ChimeraX 1.12rc202606082314\bin\Lib\site-
packages\chimerax\open_command\manager.py", line 241, in open_args  
opener_info = self.opener_info(data_format)  
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  
File "C:\Program Files\ChimeraX 1.12rc202606082314\bin\Lib\site-
packages\chimerax\open_command\manager.py", line 250, in opener_info  
return provider_info.bundle_info.run_provider(self.session,
provider_info.name, self)  
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  
File "C:\Program Files\ChimeraX 1.12rc202606082314\bin\Lib\site-
packages\chimerax\core\toolshed\info.py", line 396, in run_provider  
api = self._get_api(session.logger)  
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  
File "C:\Program Files\ChimeraX 1.12rc202606082314\bin\Lib\site-
packages\chimerax\core\toolshed\info.py", line 520, in _get_api  
m = self.get_module()  
^^^^^^^^^^^^^^^^^  
File "C:\Program Files\ChimeraX 1.12rc202606082314\bin\Lib\site-
packages\chimerax\core\toolshed\info.py", line 503, in get_module  
raise ToolshedError("Error importing bundle %s's module: %s" % (self.name,
str(e)))  
chimerax.core.toolshed.ToolshedError: Error importing bundle ChimeraX-PDB's
module: DLL load failed while importing _pdbio: An Application Control policy
has blocked this file.  
  
chimerax.core.toolshed.ToolshedError: Error importing bundle ChimeraX-PDB's
module: DLL load failed while importing _pdbio: An Application Control policy
has blocked this file.  
  
File "C:\Program Files\ChimeraX 1.12rc202606082314\bin\Lib\site-
packages\chimerax\core\toolshed\info.py", line 503, in get_module  
raise ToolshedError("Error importing bundle %s's module: %s" % (self.name,
str(e)))  
  
See log for complete Python traceback.  
  




OpenGL version: 3.3.0 - Build 32.0.101.6790
OpenGL renderer: Intel(R) Arc(TM) Graphics
OpenGL vendor: Intel

Python: 3.11.9
Locale: en_IN.cp1252
Qt version: PyQt6 6.10.2, Qt 6.10.0
Qt runtime version: 6.10.2
Qt platform: windows

Manufacturer: LENOVO
Model: 83DC
OS: Microsoft Windows 11 Pro (Build 26200.8973)
Memory: 16,766,066,688
MaxProcessMemory: 137,438,953,344
CPU: 18 Intel(R) Core(TM) Ultra 5 125H
OSLanguage: en-US

Installed Packages:
    accessible-pygments: 0.0.5
    aiohappyeyeballs: 2.6.2
    aiohttp: 3.13.4
    aiosignal: 1.4.0
    alabaster: 1.0.0
    annotated-types: 0.7.0
    anyio: 4.13.0
    appdirs: 1.4.4
    asttokens: 3.0.1
    attrs: 26.1.0
    babel: 2.18.0
    beautifulsoup4: 4.13.5
    blockdiag: 3.0.0
    blosc2: 4.4.2
    bs4: 0.0.2
    build: 1.3.0
    certifi: 2026.5.20
    cftime: 1.6.5
    charset-normalizer: 3.4.7
    ChimeraX-AddCharge: 1.5.20
    ChimeraX-AddH: 2.2.8
    ChimeraX-AlignmentAlgorithms: 2.0.2
    ChimeraX-AlignmentHdrs: 3.6.2
    ChimeraX-AlignmentMatrices: 2.1
    ChimeraX-Alignments: 3.2
    ChimeraX-AlphaFold: 1.0.1
    ChimeraX-AltlocExplorer: 1.2
    ChimeraX-AmberInfo: 1.0
    ChimeraX-Animations: 1.0
    ChimeraX-Aniso: 1.3.2
    ChimeraX-Arrays: 1.1
    ChimeraX-Atomic: 1.67.1
    ChimeraX-AtomicLibrary: 14.4
    ChimeraX-AtomSearch: 2.0.1
    ChimeraX-AxesPlanes: 2.4
    ChimeraX-BasicActions: 1.1.3
    ChimeraX-BILD: 1.0
    ChimeraX-BlastProtein: 3.0.0
    ChimeraX-Boltz: 1.1
    ChimeraX-BondRot: 2.0.4
    ChimeraX-BugReporter: 1.0.2
    ChimeraX-BuildStructure: 2.13.1
    ChimeraX-Bumps: 1.0
    ChimeraX-BundleBuilder: 1.6.0
    ChimeraX-ButtonPanel: 1.0.1
    ChimeraX-CageBuilder: 1.0.1
    ChimeraX-CellPack: 1.0
    ChimeraX-Centroids: 1.4.1
    ChimeraX-ChangeChains: 1.1
    ChimeraX-CheckWaters: 1.5
    ChimeraX-ChemGroup: 2.0.2
    ChimeraX-Clashes: 2.4
    ChimeraX-Cluster: 1.0
    ChimeraX-ColorActions: 1.0.5
    ChimeraX-ColorGlobe: 1.0
    ChimeraX-ColorKey: 1.5.8
    ChimeraX-CommandLine: 1.3.1
    ChimeraX-ConnectStructure: 2.0.1
    ChimeraX-Contacts: 1.0.1
    ChimeraX-Core: 1.12rc202606082314
    ChimeraX-CoreFormats: 1.2
    ChimeraX-coulombic: 1.4.5
    ChimeraX-Crosslinks: 1.0
    ChimeraX-Crystal: 1.0
    ChimeraX-CrystalContacts: 1.0.1
    ChimeraX-DataFormats: 1.2.4
    ChimeraX-Dicom: 1.2.7
    ChimeraX-DistMonitor: 1.4.2
    ChimeraX-DockPrep: 1.2.2
    ChimeraX-Dssp: 2.0
    ChimeraX-EMDB-SFF: 1.0
    ChimeraX-ESMFold: 1.0
    ChimeraX-FileHistory: 1.0.1
    ChimeraX-FunctionKey: 1.0.1
    ChimeraX-Geometry: 1.3
    ChimeraX-gltf: 1.0
    ChimeraX-Graphics: 1.4.1
    ChimeraX-Hbonds: 2.5.3
    ChimeraX-Help: 1.3
    ChimeraX-HKCage: 1.3
    ChimeraX-IHM: 1.1
    ChimeraX-ImageFormats: 1.2
    ChimeraX-IMOD: 1.0
    ChimeraX-IO: 1.0.4
    ChimeraX-ItemsInspection: 1.0.1
    ChimeraX-IUPAC: 1.0
    ChimeraX-KVFinder: 1.8.2
    ChimeraX-Label: 1.5
    ChimeraX-LightingGUI: 1.0
    ChimeraX-ListInfo: 1.3.1
    ChimeraX-Log: 1.2.2
    ChimeraX-LookingGlass: 1.1
    ChimeraX-Maestro: 1.9.3
    ChimeraX-Map: 1.3
    ChimeraX-MapData: 2.0
    ChimeraX-MapEraser: 1.0.1
    ChimeraX-MapFilter: 2.0.1
    ChimeraX-MapFit: 2.0
    ChimeraX-MapSeries: 2.1.1
    ChimeraX-Markers: 1.0.1
    ChimeraX-Mask: 1.0.2
    ChimeraX-MatchAlign: 1.2.1
    ChimeraX-MatchMaker: 2.4.1
    ChimeraX-MCopy: 1.0
    ChimeraX-MCPServer: 0.2.0
    ChimeraX-MDcrds: 2.19
    ChimeraX-MedicalToolbar: 1.1
    ChimeraX-Meeting: 1.0.1
    ChimeraX-Minimize: 1.3.9
    ChimeraX-MLP: 1.1.1
    ChimeraX-mmCIF: 2.16
    ChimeraX-MMTF: 2.2
    ChimeraX-ModelArchive: 1.0
    ChimeraX-Modeller: 1.5.23
    ChimeraX-ModelPanel: 1.6.1
    ChimeraX-ModelSeries: 1.0.1
    ChimeraX-Mol2: 2.0.3
    ChimeraX-Mole: 1.0
    ChimeraX-Morph: 1.0.2
    ChimeraX-MouseModes: 1.2
    ChimeraX-Movie: 1.0.1
    ChimeraX-MutationScores: 1.0
    ChimeraX-Neuron: 1.0
    ChimeraX-Nifti: 1.2
    ChimeraX-NMRSTAR: 1.0.2
    ChimeraX-NRRD: 1.2
    ChimeraX-Nucleotides: 2.0.3
    ChimeraX-OpenCommand: 1.15.4
    ChimeraX-OpenFold: 1.0
    ChimeraX-OrthoPick: 1.0.1
    ChimeraX-PDB: 2.7.13
    ChimeraX-PDBBio: 1.0.1
    ChimeraX-PDBLibrary: 1.0.5
    ChimeraX-PDBMatrices: 1.0
    ChimeraX-PickBlobs: 1.0.1
    ChimeraX-Positions: 1.0
    ChimeraX-PresetMgr: 1.1.4
    ChimeraX-ProfileGrids: 1.6
    ChimeraX-PubChem: 2.2
    ChimeraX-ReadPbonds: 1.0.1
    ChimeraX-Registration: 1.1.2
    ChimeraX-RemoteControl: 1.0
    ChimeraX-RenderByAttr: 1.8.2
    ChimeraX-RenumberResidues: 1.1
    ChimeraX-ResidueFit: 1.0.1
    ChimeraX-RestServer: 1.3.3
    ChimeraX-RNALayout: 1.0
    ChimeraX-RotamerLibMgr: 4.0
    ChimeraX-RotamerLibsDunbrack: 2.0
    ChimeraX-RotamerLibsDynameomics: 2.0
    ChimeraX-RotamerLibsRichardson: 2.0
    ChimeraX-SaveCommand: 1.5.2
    ChimeraX-Scenes: 0.3.1
    ChimeraX-SchemeMgr: 1.0
    ChimeraX-SDF: 2.0.3
    ChimeraX-Segger: 1.0
    ChimeraX-Segment: 1.0.1
    ChimeraX-Segmentations: 3.5.12
    ChimeraX-SelInspector: 1.0
    ChimeraX-SeqView: 2.18
    ChimeraX-Shape: 1.1
    ChimeraX-Shell: 1.0.1
    ChimeraX-Shortcuts: 1.2.1
    ChimeraX-ShowSequences: 1.0.3
    ChimeraX-SideView: 1.0.1
    ChimeraX-SimilarStructures: 1.0.1
    ChimeraX-Smiles: 2.1.2
    ChimeraX-SmoothLines: 1.0
    ChimeraX-SNFG: 1.0
    ChimeraX-SpaceNavigator: 1.0
    ChimeraX-StdCommands: 1.19.3
    ChimeraX-STL: 1.0.1
    ChimeraX-Storm: 1.0
    ChimeraX-StructMeasure: 1.2.1
    ChimeraX-Struts: 1.0.1
    ChimeraX-Surface: 1.0.1
    ChimeraX-SwapAA: 2.0.1
    ChimeraX-SwapRes: 2.5.3
    ChimeraX-TapeMeasure: 1.0
    ChimeraX-TaskManager: 1.0
    ChimeraX-Test: 1.0
    ChimeraX-Toolbar: 1.2.4
    ChimeraX-ToolshedUtils: 1.2.4
    ChimeraX-Topography: 1.0
    ChimeraX-ToQuest: 1.0
    ChimeraX-Tug: 1.0.1
    ChimeraX-UI: 1.50.8
    ChimeraX-Umap: 1.0
    ChimeraX-uniprot: 2.3.2
    ChimeraX-UnitCell: 1.0.1
    ChimeraX-ViewDock: 1.6.2
    ChimeraX-VIPERdb: 1.0
    ChimeraX-Vive: 1.1
    ChimeraX-VolumeMenu: 1.0.1
    ChimeraX-vrml: 1.0
    ChimeraX-VTK: 1.0
    ChimeraX-WavefrontOBJ: 1.0
    ChimeraX-WebCam: 1.0.2
    ChimeraX-WebServices: 1.1.5
    ChimeraX-Zone: 1.0.1
    click: 8.4.1
    colorama: 0.4.6
    comm: 0.2.3
    comtypes: 1.4.11
    contourpy: 1.3.3
    coverage: 7.14.1
    cxservices: 1.2.3
    cycler: 0.12.1
    Cython: 3.2.4
    debugpy: 1.8.21
    decorator: 5.3.1
    docutils: 0.21.2
    executing: 2.2.1
    filelock: 3.19.1
    fonttools: 4.63.0
    frozenlist: 1.8.0
    funcparserlib: 2.0.0a0
    glfw: 2.10.0
    grako: 3.16.5
    h11: 0.16.0
    h5py: 3.16.0
    html2text: 2025.4.15
    httpcore: 1.0.9
    httpx: 0.28.1
    httpx-sse: 0.4.3
    idna: 3.18
    ihm: 2.2
    imagecodecs: 2024.6.1
    imagesize: 2.0.0
    iniconfig: 2.3.0
    ipykernel: 7.1.0
    ipython: 9.9.0
    ipython_pygments_lexers: 1.1.1
    jedi: 0.19.2
    Jinja2: 3.1.6
    jsonschema: 4.26.0
    jsonschema-specifications: 2025.9.1
    jupyter_client: 8.8.0
    jupyter_core: 5.9.1
    kiwisolver: 1.5.0
    line_profiler: 5.0.0
    lxml: 6.0.2
    lz4: 4.3.2
    Markdown: 3.8.2
    MarkupSafe: 3.0.3
    matplotlib: 3.10.7
    matplotlib-inline: 0.2.2
    mcp: 1.18.0
    msgpack: 1.1.1
    multidict: 6.7.1
    narwhals: 2.22.1
    ndindex: 1.10.1
    nest-asyncio: 1.6.0
    netCDF4: 1.6.5
    networkx: 3.3
    nibabel: 5.2.0
    nptyping: 2.5.0
    numexpr: 2.14.1
    numpy: 1.26.4
    nvidia-nvjitlink-cu12: 12.9.86
    OpenMM: 8.4.0
    OpenMM-CUDA-12: 8.4.0
    openvr: 1.26.701
    packaging: 25.0
    ParmEd: 4.2.2
    parso: 0.8.7
    pep517: 0.13.1
    pickleshare: 0.7.5
    pillow: 11.3.0
    pip: 25.2
    pkginfo: 1.12.1.2
    platformdirs: 4.10.0
    plotly: 6.8.0
    pluggy: 1.6.0
    prompt_toolkit: 3.0.52
    propcache: 0.5.2
    psutil: 7.0.0
    pure_eval: 0.2.3
    py-cpuinfo: 9.0.0
    pybind11: 3.0.1
    pycollada: 0.8
    pydantic: 2.13.4
    pydantic-settings: 2.14.1
    pydantic_core: 2.46.4
    pydata-sphinx-theme: 0.18.0
    pydicom: 2.4.4
    Pygments: 2.18.0
    pynmrstar: 3.5.1
    pynrrd: 1.0.0
    PyOpenGL: 3.1.10
    PyOpenGL-accelerate: 3.1.10
    pyopenxr: 1.1.4501
    pyparsing: 3.3.2
    pyproject_hooks: 1.2.0
    PyQt6-commercial: 6.10.2
    PyQt6-Qt6: 6.10.2
    PyQt6-WebEngine-commercial: 6.10.0
    PyQt6-WebEngine-Qt6: 6.10.2
    PyQt6_sip: 13.10.3
    pytest: 9.0.3
    pytest-cov: 7.1.0
    python-dateutil: 2.9.0.post0
    python-dotenv: 1.2.2
    python-multipart: 0.0.32
    pywin32: 311
    pyzmq: 27.1.0
    qtconsole: 5.7.0
    QtPy: 2.4.3
    qtshim: 1.2.2
    RandomWords: 0.4.0
    referencing: 0.37.0
    requests: 2.32.5
    roman-numerals: 4.1.0
    rpds-py: 2026.5.1
    scipy: 1.14.0
    setuptools: 80.9.0
    sfftk-rw: 0.8.1
    six: 1.17.0
    snowballstemmer: 3.1.1
    sortedcontainers: 2.4.0
    soupsieve: 2.8.4
    Sphinx: 9.0.4
    sphinx-autodoc-typehints: 3.6.1
    sphinxcontrib-applehelp: 2.0.0
    sphinxcontrib-blockdiag: 3.0.0
    sphinxcontrib-devhelp: 2.0.0
    sphinxcontrib-htmlhelp: 2.1.0
    sphinxcontrib-jsmath: 1.0.1
    sphinxcontrib-qthelp: 2.0.0
    sphinxcontrib-serializinghtml: 2.0.0
    sse-starlette: 3.4.4
    stack-data: 0.6.3
    starlette: 1.2.1
    superqt: 0.7.6
    tables: 3.10.2
    tcia_utils: 3.2.1
    threadpoolctl: 3.6.0
    tifffile: 2025.3.13
    tinyarray: 1.2.5
    tornado: 6.5.7
    tqdm: 4.68.1
    traitlets: 5.14.3
    typing-inspection: 0.4.2
    typing_extensions: 4.15.0
    tzdata: 2026.2
    Unidecode: 1.4.0
    urllib3: 2.7.0
    uvicorn: 0.49.0
    wcwidth: 0.8.1
    webcolors: 24.11.1
    wheel: 0.45.1
    wheel-filename: 1.4.2
    WMI: 1.5.1
    yarl: 1.24.2
File attachment: 5V5Z.pdb

5V5Z.pdb​

[sarthak127bangar@…]

Added by email2trac

[Eric Pettersen]

Reported by Sarthak Bangar

[Greg Couch]

Hello, we have been unable to reproduce this bug locally. Can you reproduce this bug? Or does has it gone away? And can you tell more about your computer and how it is managed? Is it a business laptop or computer managed by corporate IT? Does it use Microsoft Defender for anti-virus software or something else (eg., Bitdefender, Sophos, Norton, Malwarebytes, etc.)?

And what do you see if you right-click to see the Properties of C:\Program Files\ChimeraX 1.12rc202606082314\bin\Lib\site-packages\chimerax\pdb\_pdbio.cp314-win_amd64.pyd ? Does it say that the file might be blocked and why?

Any other clue you think might be relevant?