Comment 1 for bug 2030110

I have found this issue as well, in loki-k8s:

unit-loki-k8s-0: 13:40:44.893 INFO juju.worker.uniter found queued "upgrade-charm" hook
unit-loki-k8s-0: 13:40:45.069 WARNING unit.loki-k8s/0.upgrade-charm ModuleNotFoundError: No module named '_cffi_backend'
unit-loki-k8s-0: 13:40:45.069 WARNING unit.loki-k8s/0.upgrade-charm thread '<unnamed>' panicked at 'Python API call failed', /github/home/.cargo/registry/src/index.crates.io-6f17d22bba15001f/pyo3-0.18.3/src/err/mod.rs:790:5
unit-loki-k8s-0: 13:40:45.069 WARNING unit.loki-k8s/0.upgrade-charm note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
unit-loki-k8s-0: 13:40:45.069 WARNING unit.loki-k8s/0.upgrade-charm Traceback (most recent call last):
unit-loki-k8s-0: 13:40:45.069 WARNING unit.loki-k8s/0.upgrade-charm File "./src/charm.py", line 33, in <module>
unit-loki-k8s-0: 13:40:45.069 WARNING unit.loki-k8s/0.upgrade-charm from charms.observability_libs.v0.cert_handler import CertHandler
unit-loki-k8s-0: 13:40:45.069 WARNING unit.loki-k8s/0.upgrade-charm File "/var/lib/juju/agents/unit-loki-k8s-0/charm/lib/charms/observability_libs/v0/cert_handler.py", line 41, in <module>
unit-loki-k8s-0: 13:40:45.069 WARNING unit.loki-k8s/0.upgrade-charm from charms.tls_certificates_interface.v2.tls_certificates import ( # type: ignore
unit-loki-k8s-0: 13:40:45.069 WARNING unit.loki-k8s/0.upgrade-charm File "/var/lib/juju/agents/unit-loki-k8s-0/charm/lib/charms/tls_certificates_interface/v2/tls_certificates.py", line 285, in <module>
unit-loki-k8s-0: 13:40:45.069 WARNING unit.loki-k8s/0.upgrade-charm from cryptography import x509
unit-loki-k8s-0: 13:40:45.069 WARNING unit.loki-k8s/0.upgrade-charm File "/var/lib/juju/agents/unit-loki-k8s-0/charm/venv/cryptography/x509/__init__.py", line 7, in <module>
unit-loki-k8s-0: 13:40:45.069 WARNING unit.loki-k8s/0.upgrade-charm from cryptography.x509 import certificate_transparency
unit-loki-k8s-0: 13:40:45.069 WARNING unit.loki-k8s/0.upgrade-charm File "/var/lib/juju/agents/unit-loki-k8s-0/charm/venv/cryptography/x509/certificate_transparency.py", line 11, in <module>
unit-loki-k8s-0: 13:40:45.069 WARNING unit.loki-k8s/0.upgrade-charm from cryptography.hazmat.bindings._rust import x509 as rust_x509
unit-loki-k8s-0: 13:40:45.069 WARNING unit.loki-k8s/0.upgrade-charm pyo3_runtime.PanicException: Python API call failed
unit-loki-k8s-0: 13:40:45.281 ERROR juju.worker.uniter.operation hook "upgrade-charm" (via hook dispatching script: dispatch) failed: exit status 1