Ubuntu 16.04 LTS failed to mount CIFS share at boot

📖 ~1 min read

Table of contents

1. Symptom & Impact
2. Environment & Reproduction
3. Root Cause Analysis
4. Quick Triage
5. Step-by-Step Diagnosis
6. Solution – Primary Fix
7. Solution – Alternative Approaches
8. Verification & Acceptance Criteria
9. Rollback Plan
10. Prevention & Hardening
11. Related Errors & Cross-Refs
12. References & Further Reading

Symptom & Impact

System boot slows or fails because remote SMB share cannot be mounted during startup.

Environment & Reproduction

Seen when network becomes ready after mount attempt or credentials file is invalid.

Root Cause Analysis

fstab mount ordering and network dependencies are misconfigured for CIFS requirement timing.

Quick Triage

Test manual mount with same options and validate credential and DNS resolution first.

Step-by-Step Diagnosis

Review boot logs and systemd mount units to confirm dependency and timeout behavior.

Solution – Primary Fix

Add _netdev and automount-safe options, then reload daemon and retest boot flow.

Solution – Alternative Approaches

Mount on-demand with autofs or application startup scripts after network readiness.

Verification & Acceptance Criteria

Host boots normally and share mounts reliably without manual intervention.

Rollback Plan

Disable fstab entry temporarily and restore prior mount mechanism.

Prevention & Hardening

Use robust credential management and monitor remote share availability.

Related Errors & Cross-Refs

mount error(115), dependency failed for remote file systems, and permission denied.

Related tutorial: View the step-by-step tutorial for Ubuntu 16.04 LTS.

View all Ubuntu 16.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

CIFS mount reliability patterns for Ubuntu 16.04 servers.