Closed mid-transfer
Likely causes
- - Upstream reset mid-response
- - Keep-alive window mismatch
Verified remedy
Retry once, then lower concurrency and raise client timeouts; keep the endpoint fixed.
Proxy troubleshooting
Fix ERR_CONNECTION_CLOSED through a proxy
Ranked causes, ordered diagnostics, and a verified remedy for err_connection_closed through a proxy - ending with a final connection check.
Quick answer
Fix: connection closed while using a proxy. Confirm endpoint values, test with curl through the endpoint, apply the matched remedy, then re-verify the exit IP is your assigned endpoint.
Exact symptom text
Causes ranked by likelihood
Ordered diagnostics
Final connection check
When this is the right fit
- Exact symptom text
- Causes ranked by likelihood
- Ordered diagnostics
Who this page is for
Ranked causes, ordered diagnostics, and a verified remedy for err_connection_closed through a proxy - ending with a final connection check.
Fix: connection closed while using a proxy. Confirm endpoint values, test with curl through the endpoint, apply the matched remedy, then re-verify the exit IP is your assigned endpoint.
Diagnosis tree
Final connection check
- 1Apply the matched remedy
- 2Test the endpoint with curl
- 3Repeat the original action
- 4Confirm the exit IP is the assigned endpoint
Working connection
The action completes and the exit IP matches the endpoint.
Broken connection
If curl also fails, the endpoint is unhealthy: swap to a spare.
Sources
Facts last reviewed 2026-09-01.
Prevent it recurring
Keep one profile on one static endpoint, verify exit IPs daily, and rotate credentials on a documented schedule.
195+ countries
99.9% uptime guarantee
Unlimited bandwidth
4.9/5 from 127 ratings
Frequently asked questions
How do I fix ERR_CONNECTION_CLOSED through a proxy?
Work the diagnosis tree top to bottom, confirm endpoint values, test with curl through the endpoint, then run the final connection check.
Choose one stable proxy for every active profile
Buy self-serve now, or talk with us about a larger agency inventory.