π ~1 min read
Table of contents
Symptom & Impact
Package installation fails because dependency versions cannot be satisfied by enabled repositories.
Environment & Reproduction
Often reproduced after mixed repositories, manual pinning, or partially upgraded package sets.
Root Cause Analysis
Pinned or held packages prevent resolver from selecting coherent versions for all dependencies.
Quick Triage
List held packages and check apt policy output before forcing package removal.
Step-by-Step Diagnosis
Run apt-mark showhold, apt-cache policy, and simulate install to inspect resolver decisions.

Solution – Primary Fix
Unhold conflicting packages, align repositories, and execute apt -f install followed by full-upgrade.
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Solution – Alternative Approaches
Use targeted version pinning with clear priorities when coexistence of repository streams is required.
Verification & Acceptance Criteria
No unmet dependency messages remain and simulated upgrades resolve cleanly.
Rollback Plan
Reapply previous hold and pinning files if upgraded package set introduces incompatibility.
Prevention & Hardening
Avoid mixing release branches and document any package pinning with expiry review dates.
Related Errors & Cross-Refs
Unable to correct problems; held broken packages; depends but it is not installable.
Related tutorial: View the step-by-step tutorial for debian-12.
View all debian-12 tutorials on the Tutorials Hub β
Browse all common problems & solutions on the Tutorials Hub.
References & Further Reading
APT pinning manual, Debian package dependency policy, and release upgrade guidance.
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