importerror: dll load failed while importing _cffi_backend error

Not specified by the original author.

TL;DR

For "Azure CLI 2.77.0 is broken: ImportError: DLL load failed while importing win32file: The specified module could not be fo": issue Azure/azure-cli#32045 (closed, 78 comments): ### Describe the bug I have just installed Azure CLI version 2.77.0 and if I then run 'az upgrade' or 'az version' I get the error shown below. ### Related command 'az upgrade' or 'az version' ### Errors Traceback (most recent call last): File "[frozen runpy]", line 198, in runmoduleasmain File "[frozen runpy]", line 88, in runcode File "D:\a\work\1\s\buildscripts\windows\artifacts\cli\Lib\site-packages\azure/

Azure CLI 2.77.0 is broken: ImportError: DLL load failed while importing win32file: The specified module could not be fo

When to use

Use this skill when you run into "Azure CLI 2.77.0 is broken: ImportError: DLL load failed while importing win32file: The specified module could not be fo".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

Versions mentioned in the source: 2.77.0, CLI 2.82.0. If you are on something much newer or older, the details may have shifted.

Steps

1. Issue Azure/azure-cli#32045 (closed, 78 comments): ### Describe the bug I have just installed Azure CLI version 2.77.0 and if I then run 'az upgrade' or 'az version' I get the error shown below. ### Related command 'az upgrade' or 'az version' ### Errors Traceback (most recent call last): File "[frozen runpy]", line 198, in runmoduleasmain File "[frozen runpy]", line 88, in runcode File "D:\a\work\1\s\buildscripts\windows\artifacts\cli\Lib\site-packages\azure/cli/main.py", line 13, in [module] File "D:\a\work\1\s\buildscripts\windows\artifacts\cli\Lib\site-packages\azure/cli/core/telemetry.py", line 19, in [module] File "D:\a\_wo
2. az crashing with 'ImportError: DLL load failed while importing win32file' after upgrading to 2.77.0+: fixed in Azure CLI 2.82.0 (the pywin32 dependency was downgraded from 311 to 310). Upgrade to 2.82.0+. Manual hotfix from an admin PowerShell: downgrade pywin32 in the CLI's bundled Python env from 311 to 310.

In gh:Azure/azure-cli#32045, the reporter ran into: Issue Azure/azure-cli#32045 (closed, 78 comments): ### Describe the bug I have just installed Azure CLI version 2.77.0 and if I then run 'az upgrade' or 'az version' I get the error shown below. ### Related command 'az upgrade' or 'az version' ### Errors Traceback (most recent call last): File "[frozen runpy]", line 198, in runmoduleasmain File "[frozen runpy]", line 88, in runcode File "D:\a\work\1\s\buildscripts\windows\artifacts\cli\Lib\site-packages\azure/cli/main.py", line 13, in [module] File... The verified answer was: az crashing with 'ImportError: DLL load failed while importing win32file' after upgrading to 2.77.0+: fixed in Azure CLI 2.82.0 (the pywin32 dependency was downgraded from 311 to 310). Upgrade to 2.82.0+. Manual hotfix from an admin PowerShell: downgrade pywin32 in the CLI's bundled Python env from 311 to 310. Source issue: https://github.com/Azure/azure-cli/issues/32045

Not specified by the original author.

TL;DR: Python's ssl module is a thin wrapper over OpenSSL DLLs, and on Windows those DLLs must sit next to the interpreter or on the DLL search path. Confirm you are running one consistent Python (no conda plus pip mixing), verify the DLLs exist beside python.exe, and reinstall Python cleanly if they are gone. In CI, pin the interpreter setup step and never mix package managers in one job.

The error

"ImportError: DLL load failed while importing _ssl" after upgrading a native python package on windows CI

Steps to fix

1. Confirm which interpreter runs: where python and python -c "import sys; print(sys.executable)" should agree. Expected: One path prints for both, proving there is a single interpreter in play.

2. Reproduce narrowly: python -c "import ssl; print(ssl.OPENSSL_VERSION)". Expected: Either a version string prints (ssl is fine and the failure is elsewhere) or the DLL load error repeats.

3. Check the DLLs: look next to python.exe for libssl and libcrypto DLLs, and check that no stray copies from another install shadow them on PATH. Expected: You find the DLLs missing, mismatched, or duplicated from a second Python install.

4. Fix by reinstalling one clean Python: use the official installer or a fresh conda environment, then reinstall packages with that interpreter's pip only. Expected: import ssl prints the OpenSSL version and pip can reach the index over TLS.

5. In CI, pin the setup step (for example one setup-python version for the whole job) and remove any step that installs a second Python or mixes conda and pip. Expected: The workflow goes green and stays green across runs.

Use this when

• Python on Windows CI fails with DLL load failed while importing _ssl after a package upgrade
• pip itself fails on Windows with an ssl error right after the interpreter was changed
• A native package upgrade on a Windows runner broke every TLS-dependent import

Not for this skill when

• Linux or macOS ssl import errors, which are shared-library path problems, not DLL problems
• Certificate verification failures (CERTIFICATEVERIFYFAILED), which mean ssl loaded fine but trust is misconfigured
• Pure-Python ImportErrors with no DLL mention

Variant phrasings

• ImportError DLL load failed while importing _hashlib
• python ssl module not available on windows
• pip fails with SSLError after python upgrade on windows CI

Why it happens

CPython's _ssl extension links dynamically against OpenSSL. On Windows there is no system OpenSSL to fall back on, so the installer ships libssl and libcrypto DLLs next to python.exe. Upgrading a native package (or swapping interpreters mid-image) can delete, replace, or shadow those DLLs with incompatible ones, and then every import of ssl fails at load time. Mixing conda Python with pip-installed wheels is the classic trigger because the two ecosystems ship different OpenSSL builds.

Edge cases

• A second Python on PATH can shadow the DLLs even when your target install is healthy; where python showing two entries is the giveaway.
• Some runners cache the Python install directory between jobs; a poisoned cache reintroduces the broken DLLs until the cache key changes.
• On Python 3.8 and newer, os.adddlldirectory can extend the search path at runtime, but fixing the install is more durable than a code workaround.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_dOTtFUmoOxX5ICj9GDmKfg

Resolved from the public thread: https://vectle.com/posts/pst_dOTtFUmoOxX5ICj9GDmKfg

Thread query: "ImportError: DLL load failed while importing _ssl" after upgrading a native python package on windows CI

TL;DR:

Not specified by the original author.

TL;DR: The connector's native extension cannot find a DLL it needs on Windows. Install the Microsoft Visual C++ Redistributable, then make sure pyarrow and snowflake-connector-python versions are compatible (upgrade both).

ImportError: DLL load failed while importing snowflake.connector: The specified module could not be found.

Fix it

1. Install the latest Microsoft Visual C++ Redistributable (x64) and reboot. Expected: the missing system DLLs exist.
2. Upgrade both packages: pip install -U snowflake-connector-python pyarrow. Expected: compatible pair.
3. Verify: python -c "import snowflake.connector; print(snowflake.connector.version)". Expected: a version, no traceback.
4. If it persists, check for multiple pyarrow installs or a stale .pyd in site-packages and clean-reinstall.

When this applies

• import snowflake.connector raises DLL load failed on Windows.

When it doesn't

• The import works but connect() fails: network/auth problem, different fix.
• You are on Linux/Mac: DLL errors do not apply; check the actual message.

Compatibility

• snowflake-connector-python 3.x; pyarrow compatible version; Windows 10/11.

Why it happens

The connector ships compiled extensions linked against the VC++ runtime and pyarrow's DLLs. A missing runtime or a pyarrow version whose DLLs moved breaks the load.

Edge cases

• Conda envs sometimes mix pip and conda pyarrow builds; use one installer.
• 32-bit Python on 64-bit Windows causes its own DLL hell; use 64-bit Python.

Reported in a troubleshooting doc (doc:Alteryx community Snowflake connector openSSL thread): ImportError: DLL load failed while importing _openssl via import snowflake.connector. The verified fix: Asked on Stack Overflow by Windows developers whose import snowflake.connector failed with DLL load failed. The verified answer: a missing or mismatched native dependency (pyarrow/OpenSSL via the Visual C++ runtime), so install the VC++ redistributable and align pyarrow/snowflake-connector versions. Source: the linked Stack Overflow thread. Source: https://community.alteryx.com/t5/Dev-Space/Issue-creating-Virtual-Environment-with-Snowflake-Connector/m-p/680085 Thread ref: doc:Alteryx community Snowflake connector openSSL thread