📖 ~1 min read
Table of contents
Symptom & Impact
Application service fails with module-not-found or bad interpreter errors.
Environment & Reproduction
Appears after directory rename, deployment move, or virtualenv recreation.
Root Cause Analysis
Service/scripts still reference old virtualenv interpreter and site-packages path.
Quick Triage
Check runtime path with `which python3` and inspect unit `ExecStart` values.
Step-by-Step Diagnosis
Validate shebang lines and service environment variables against current venv location.
Solution – Primary Fix
Update unit/script paths to current venv, reinstall dependencies, and restart service.
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Solution – Alternative Approaches
Recreate venv in canonical path and keep symlink for backward compatibility.
Verification & Acceptance Criteria
Service starts cleanly and imports required packages successfully.
Rollback Plan
Revert to previous deployment bundle if path update introduces new issues.
Prevention & Hardening
Pin interpreter paths in deployment templates and avoid ad-hoc directory moves.
Related Errors & Cross-Refs
Related to mixed system/venv pip installs and stale wheel caches.
Related tutorial: View the step-by-step tutorial for debian-10.
View all debian-10 tutorials on the Tutorials Hub →
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
Debian Python packaging and virtualenv best practices.
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