PR_CONNECT_RESET_ERROR: Causes, Fixes, and Troubleshooting Guide
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Last Updated: Aug 25, 2026
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Firefox Connection Reset Blocking Your Website?
If Firefox shows PR_CONNECT_RESET_ERROR, the connection may be interrupted by SSL, proxy, firewall, or server configuration issues. Find the root cause and restore reliable website access.
- SSL/TLS configuration checks
- Proxy & firewall debugging
- Server connection analysis
- Network issue resolution
The PR_CONNECT_RESET_ERROR is a Firefox connection error that appears when the browser begins establishing a secure connection with a website, but the connection is unexpectedly reset before it can complete. In most cases, the reset comes from the destination server, a router, a firewall, an antivirus product, a proxy, or another security layer positioned between Firefox and the website. Mozilla support discussions describe the error as a situation where the server or an intermediate device tells Firefox to terminate the connection.
The issue may affect one website, several HTTPS websites, or, in some cases, almost every website in Firefox. Other browsers may continue working normally, which can make the problem appear Firefox-specific even when the real cause is a security product, TLS configuration, network filter, or a browser profile setting.
This guide explains what PR_CONNECT_RESET_ERROR means, its most common causes, how to fix it step by step, how to diagnose server-side problems, and the best practices for preventing similar connection errors.
What Does PR_CONNECT_RESET_ERROR Mean?
PR_CONNECT_RESET_ERROR means that Firefox attempted to create a network connection, but the connection was reset before the requested page could be loaded. Instead of receiving a normal HTTPS response, Firefox receives a connection reset signal.
A simplified connection flow looks like this:
Firefox
↓
DNS Resolution
↓
TCP Connection
↓
TLS Handshake
↓
Website Server
When the connection is reset somewhere during that process, Firefox may display:
Secure Connection Failed
An error occurred during a connection to example.com.
PR_CONNECT_RESET_ERROR
The reset can occur on the web server itself or on an intermediate security device. Mozilla support contributors specifically note that a server, router, firewall, or security service can terminate the connection, triggering this error.
Why Does PR_CONNECT_RESET_ERROR Occur?
There is no single cause of PR_CONNECT_RESET_ERROR. The error describes what happened to the connection, not necessarily why it happened.
The real cause can be on your device, on your local network, in your browser configuration, in your security software, or on the remote web server.
Firewall or Security Software Is Resetting the Connection
Antivirus and internet-security products sometimes inspect HTTPS traffic. To do this, they may intercept TLS connections and present their own certificates to the browser.
If the inspection fails or Firefox rejects the modified connection, the security software may reset it. Mozilla support discussions have specifically identified antivirus and security products that intercept secure connections as possible causes of Firefox connection failures.
Temporarily testing without HTTPS scanning can help identify whether security software is responsible, but permanently disabling protection is not a good solution.
VPN or Proxy Configuration Problems
A VPN or proxy adds another layer of network connectivity between Firefox and the website. If the proxy cannot establish the HTTPS connection or terminates the connection unexpectedly, Firefox may report PR_CONNECT_RESET_ERROR.
This can happen because of:
- Incorrect proxy settings
- Unavailable VPN servers
- Corporate web filtering
- TLS inspection
- Authentication failures
- Restricted destination websites
Checking the connection without the VPN or proxy can help isolate the issue.
Server-Side TLS Configuration Problems
The destination server may be configured with TLS settings that Firefox cannot negotiate correctly.
For example, the server might support only outdated cipher suites or contain a broken TLS configuration. One Mozilla support case identified lack of compatible encryption ciphers between Firefox and the server as the reason for the reset.
In this situation, the user may not be able to solve the problem locally. The website administrator must correct the server configuration.
Network or Router Problems
Routers, enterprise gateways, ISP filtering systems, and network security appliances can terminate connections.
For example:
Firefox
↓
Router
↓
Firewall
X Connection Reset
↓
Website
Restarting the router may resolve temporary problems, but persistent resets may require checking firewall rules or network filtering policies.
Firefox Extensions
Extensions can modify requests, block trackers, intercept connections, or alter network behavior.
There are documented cases in Mozilla Support where disabling an extension resolved PR_CONNECT_RESET_ERROR.
Troubleshoot Mode is therefore an important diagnostic tool because it temporarily disables extensions and several customizations.
Corrupted Firefox Profile or Certificate Database
Firefox stores certificates and security-related information inside the browser profile.
If profile data becomes corrupted, Firefox may fail when creating secure connections. In one Mozilla support case involving TLS/SSL sites, recreating the cert9.db certificate database resolved the problem.
This should usually be attempted only after simpler troubleshooting steps have failed.
Encrypted Client Hello or Firewall Compatibility
Modern browsers increasingly use newer TLS privacy features such as Encrypted Client Hello (ECH). Some firewalls and network security devices may not handle these features correctly.
A Mozilla support case involving PR_CONNECT_RESET_ERROR was eventually traced to firewall rules that were blocking part of the ECH handshake.
This type of issue is more likely in enterprise networks using advanced TLS inspection.
How to Fix PR_CONNECT_RESET_ERROR Step by Step?
The best troubleshooting approach is to start with simple browser and network checks before changing advanced Firefox or operating-system settings.
Test the affected website after each step. This helps identify which change actually fixes the issue.
Step 1: Reload the Website and Test Another Site
Start with a normal refresh:
Ctrl + R
or use:
Ctrl + Shift + R
for a forced reload.
Then test several websites.
If only one website fails, the problem may be server-side. If every HTTPS website fails, the problem is more likely related to Firefox, security software, or your network.
Step 2: Test the Website in Another Browser
Open the same URL in Chrome, Edge, Safari, or another available browser.
There are three useful outcomes:
| Result | Likely Direction |
|---|---|
| Fails in every browser | Network or website problem |
| Works elsewhere but not Firefox | Firefox, extension, profile, or TLS compatibility |
| Fails only on one network | Router, ISP, proxy, or firewall |
| Fails only on one website | Server configuration likely |
Do not assume that Firefox itself is broken just because another browser works. Different browsers can negotiate TLS or network features differently.
Step 3: Restart Firefox and Your Computer
Close Firefox completely and reopen it.
If the problem continues, restart the computer. This clears temporary network processes, browser background services, and stale connections.
If the error started suddenly without configuration changes, a restart is a quick diagnostic step before deeper troubleshooting.
Step 4: Restart the Router
Turn off the router or modem, wait briefly, and restart it.
After the internet connection returns, retry the website.
If the problem affects multiple devices on the same network, router or ISP-level filtering becomes more likely.
Step 5: Clear Firefox Cache and Site Data
Corrupted cached content or site data can sometimes interfere with connections and authentication flows.
In Firefox:
Settings
→ Privacy & Security
→ Cookies and Site Data
→ Clear Data
You can also remove data for only the affected website instead of clearing everything.
Mozilla support contributors have recommended clearing affected-site cookies and storage while diagnosing connection-reset problems.
Step 6: Use Firefox Troubleshoot Mode
Troubleshoot Mode temporarily disables extensions, themes, and some hardware acceleration settings.
Open:
Menu
→ Help
→ Troubleshoot Mode
Restart Firefox when prompted.
If the website works in Troubleshoot Mode, an extension or browser customization is likely responsible. One Mozilla support case found that disabling a privacy/security extension resolved PR_CONNECT_RESET_ERROR.
Re-enable extensions individually until you find the conflicting one.
Step 7: Disable VPN or Proxy Temporarily
If you are using a VPN, disconnect it temporarily and test again.
Then check Firefox proxy settings:
Settings
→ General
→ Network Settings
→ Settings
If your network does not require a manual proxy, verify that Firefox is not configured to use an outdated proxy server.
Do not permanently remove an organization-required proxy. If the issue occurs on a managed corporate network, contact the network administrator.
Step 8: Check Antivirus HTTPS Scanning
Security products may contain features named:
HTTPS Scanning
Encrypted Connection Scanning
SSL Inspection
Web Shield
Secure Web
Temporarily disabling only the HTTPS-inspection function can help determine whether it is causing the connection reset.
Do not disable the entire security product longer than necessary for testing.
If HTTPS scanning is confirmed as the cause, update the security software and review its certificate or Firefox integration settings.
Step 9: Check System Date and Time
TLS connections depend on valid certificates, and certificate verification depends on system time.
Make sure your:
Date
Time
Time zone
are correct.
Enable automatic time synchronization where available.
A significantly incorrect clock can cause secure connections and certificate validation to behave unexpectedly.
Step 10: Flush the DNS Cache
A stale DNS record may direct Firefox to an incorrect server or network endpoint.
On Windows, open Command Prompt as Administrator:
ipconfig /flushdns
You should see:
Successfully flushed the DNS Resolver Cache.
Then restart Firefox.
Firefox also maintains networking information internally, so restarting the browser after flushing DNS is useful.
Step 11: Change DNS Provider
If DNS resolution appears unreliable, temporarily test another reputable DNS provider.
For example:
Cloudflare:
1.1.1.1
1.0.0.1
Google:
8.8.8.8
8.8.4.4
If the website works after changing DNS, the previous resolver may have been returning an incorrect or filtered response.
However, on company networks, changing DNS may bypass required internal resolution and should be done only with administrator approval.
Step 12: Check Firefox DNS Over HTTPS
Firefox can use DNS over HTTPS (DoH), depending on configuration and network policy.
Navigate to:
Settings
→ Privacy & Security
→ DNS over HTTPS
Try switching the setting temporarily and retesting.
The goal is not to permanently disable encrypted DNS, but to determine whether the current DNS path contributes to the issue.
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How Does Moon Technolabs Help With Web, Server, and Network Troubleshooting?
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Whether a PR_CONNECT_RESET_ERROR is caused by an incorrectly configured web server, TLS incompatibility, a reverse proxy, a firewall, a load balancer, a CDN, or a cloud environment, Moon Technolabs can help identify the root cause and implement a stable solution.
We also help organizations improve application monitoring, secure server configurations, cloud deployments, and production reliability so that connectivity issues can be detected and resolved before they significantly affect users.
Struggling With Persistent Web or Server Connection Issues?
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Conclusion
The PR_CONNECT_RESET_ERROR occurs when Firefox’s connection to a website is unexpectedly terminated by the server or something positioned between the browser and that server. Possible causes include security software, firewalls, VPNs, proxies, browser extensions, TLS incompatibilities, corrupted Firefox profile data, and website infrastructure problems.
The best troubleshooting process is to first determine whether the problem affects one website or many, compare Firefox with another browser, use Troubleshoot Mode, inspect VPN and proxy settings, check security software, and test the network connection. Advanced fixes such as refreshing the Firefox profile or rebuilding the certificate database should come later.
For website owners, the investigation should also include TLS settings, server logs, CDN behavior, WAF rules, and modern TLS features such as ECH. A structured diagnosis helps fix the actual source of the reset instead of relying on temporary browser workarounds.
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