🟑 Medium   ⏱ 5–30 min  Last verified: 19 May 2026
Affected versions: Ubuntu 26.04 LTS

πŸ“– ~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

snap refresh fails and Snap Store reports connectivity errors, delaying application updates.

Environment & Reproduction

Observed behind restrictive proxies, DNS failures, or broken snapd state.

snap version
systemctl status snapd --no-pager
resolvectl status
curl -I https://api.snapcraft.io

Root Cause Analysis

snapd cannot resolve endpoints or establish TLS sessions due to DNS, proxy, or certificate path issues.

Quick Triage

Check service health, socket activation, and direct HTTPS reachability.

systemctl is-active snapd
systemctl status snapd.socket --no-pager
snap changes
journalctl -u snapd -n 100 --no-pager

Step-by-Step Diagnosis

Validate DNS and proxy behavior while reproducing a refresh operation.

resolvectl query api.snapcraft.io
env | grep -i proxy
snap refresh --list
snap debug connectivity
Illustrative mockup for ubuntu-26-04-lts β€” terminal_or_shell
Diagnostic output for snap/connectivity β€” Illustrative mockup β€” Progressive Robot

Solution – Primary Fix

Restart snapd, clear stuck changes, and restore network resolver consistency.

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sudo systemctl restart snapd snapd.socket
sudo snap abort --last=auto-refresh
sudo snap refresh
sudo resolvectl flush-caches
Illustrative mockup for ubuntu-26-04-lts β€” log_or_console
Resolution output for snap/connectivity β€” Illustrative mockup β€” Progressive Robot

Solution – Alternative Approaches

If proxy is mandatory, set explicit snapd proxy values.

sudo snap set system proxy.http=http://PROXY:PORT
sudo snap set system proxy.https=http://PROXY:PORT
sudo snap get system proxy

Verification & Acceptance Criteria

Problem is resolved when snap refresh and Snap Store operations complete without timeout or TLS errors.

snap refresh --list
snap refresh
snap changes
journalctl -u snapd -n 30 --no-pager

Rollback Plan

If changes break connectivity, revert proxy settings and restart snapd.

sudo snap unset system proxy.http
sudo snap unset system proxy.https
sudo systemctl restart snapd

Prevention & Hardening

Monitor snapd health and standardize DNS and proxy policy across hosts.

systemctl enable snapd
snap set system refresh.timer=00:00-04:00
resolvectl statistics

Related messages include cannot refresh, connection reset, DNS lookup failed, and proxy authentication required.

Related tutorial: View the step-by-step tutorial for Ubuntu 26.04 LTS.

View all Ubuntu 26.04 LTS tutorials on the Tutorials Hub β†’

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

snapd documentation, Snapcraft networking notes, and Ubuntu DNS resolver guidance.

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