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PR_END_OF_FILE_ERROR means Firefox’s secure connection ended before the browser could complete its HTTPS handshake. It does not, by itself, prove that a website’s certificate is invalid or that the site is unsafe. Start by checking whether one site or many fail, then test the most common local causes: a VPN, Firefox DNS over HTTPS (DoH), proxy settings, antivirus HTTPS inspection, and the computer’s clock.
- Reload the page and try another unrelated HTTPS site.
- Disconnect your VPN briefly, then retry.
- Temporarily turn off Firefox DoH.
- Review Firefox’s proxy setting.
- Test antivirus HTTPS inspection, then restore it.
- Check the date, time, and time zone; update Firefox and relevant security software.
- If the problem persists, try another network and use the results below to decide whether to contact the site or your network administrator.
What does PR_END_OF_FILE_ERROR mean?
Firefox displays this error when a secure connection ends before the browser receives the data it needs to establish HTTPS. The code points to an incomplete connection, not a single cause. The interruption can come from Firefox settings, a VPN or proxy, security software inspecting encrypted traffic, a network, or the website’s TLS setup.
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Mozilla lists VPNs, DNS over HTTPS, antivirus or other software that intercepts encrypted connections, and incorrect proxy settings among practical causes. A wrong system clock or certificate data can also interfere with secure connections. Older Mozilla support discussions mention cipher-suite negotiation as one possible explanation, but that is not a reliable diagnosis for every occurrence: Mozilla support discussion of cipher suites and another Mozilla support discussion.
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1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsThere is no general “Accept the Risk and Continue” bypass for this error. Do not lower Firefox’s TLS security or disable certificate checks to force a connection. Mozilla’s secure-connection troubleshooting guidance explains that some secure-connection failures cannot be bypassed with a security exception.
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First find out how widespread the problem is
Before changing settings, try the affected address in another browser, on another device, and on another network if available. Each comparison narrows the likely cause; none alone proves which component is responsible.
| What you observe | What it suggests | Best next test |
|---|---|---|
| Several unrelated sites fail only in Firefox | Firefox configuration or software interacting with Firefox is more likely. | Check VPN, DoH, proxy, and encrypted-traffic inspection. |
| One site fails only while a VPN is connected | The VPN route, server, DNS handling, or inspection may be involved. | Disconnect the VPN; if the site then works, try another VPN server or protocol. |
| One site fails only in Firefox | A Firefox setting, profile, or Firefox-specific software interaction is possible. | Check DoH and proxy settings, then try Troubleshoot Mode. |
| All browsers fail on one computer | System software, clock, firewall, or network configuration may be involved. | Check system time and security software; test another network. |
| All devices fail on one Wi-Fi network | The router, ISP, DNS service, firewall, or network policy may be involved. | Try a cellular hotspot or another network. |
| The site fails across browsers, devices, and networks | A site-side or domain-specific problem becomes more plausible. | Contact the site administrator; do not assume the code alone proves a server fault. |
A Mozilla support case, for example, describes this error affecting Amazon rather than every website, illustrating why a one-site failure should be diagnosed separately: Mozilla support case. Also, a site loading in Chrome does not prove Firefox is defective: browsers can differ in networking behavior and in how they interact with proxies, certificate stores, and security software.
Fixes to try, in order
1. Disconnect the VPN temporarily
A VPN can change traffic routing and DNS handling, or include web protection and traffic inspection. Disconnect it briefly, reload the affected page, and reconnect it after the test. If the site works without the VPN, try a different VPN server or protocol and update the VPN app. Check whether its settings include HTTPS inspection, web protection, custom DNS, or an integrated proxy.
A VPN and DoH are separate layers: the VPN routes traffic, while Firefox DoH changes how Firefox looks up domain names. Their interaction can matter. In one Mozilla support case involving Proton VPN, disabling Firefox DoH resolved the reported error; that example does not establish that every VPN or every instance of the error has the same cause.
2. Temporarily turn off DNS over HTTPS
On Firefox desktop, open Menu → Settings → Privacy & Security, then find DNS over HTTPS. Temporarily set its protection level to Off, or use a site exception if that option is available, and retry the page. Labels and available controls may differ by Firefox release or region; see Mozilla’s Firefox DNS-over-HTTPS settings guide and DoH FAQs.
If this test works, it implicates DNS handling or something interacting with it, such as a VPN, security product, ISP filtering, or local network policy. Turning off DoH changes how DNS lookups are handled; it does not repair a website’s TLS certificate. Treat the change as a diagnostic step and investigate the conflicting component before leaving privacy protections disabled.
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3. Review Firefox’s proxy settings
In Firefox desktop, open Menu → Settings → General, scroll to Network Settings, and select Settings…. For a direct-connection test, select No proxy, save, and retry. On a computer that intentionally uses an organization’s proxy, keep the required configuration and ask the administrator for help instead. Use Use system proxy settings when that is the correct configuration for your device; choose Manual proxy configuration only if you have valid proxy details. Mozilla documents this panel in its Firefox connection settings guide.
4. Test antivirus or security-software HTTPS inspection
Some security products inspect encrypted traffic and sit between Firefox and a website. Update the product first. If the error persists, look for a setting called HTTPS scanning, SSL scanning, encrypted-traffic inspection, TLS inspection, or web protection. Temporarily turn off only that feature, if possible, test the site, and turn it back on immediately afterward.
If disabling inspection fixes the connection, update the product or contact its vendor to correct the compatibility issue. Do not leave antivirus protection or a firewall disabled as a general fix. Mozilla’s secure-connection guidance recommends keeping security software current and investigating whether it is interfering. Its advice about considering removal of an outdated third-party security product and using Microsoft Defender applies to Windows; it should not be treated as a general macOS or Linux instruction.
5. Correct the computer’s clock
An incorrect date, time, or time zone can make a valid certificate appear expired or not yet valid. Enable automatic date and time in your operating system’s settings, confirm the time zone, restart Firefox, and retry. This check is especially useful after a dead laptop battery, firmware changes, dual-boot setup, long periods offline, or a new operating-system installation.
6. Update Firefox and related software
Install available Firefox updates, then update the VPN and security software involved in the tests. Compatibility problems can arise in software that handles encrypted connections. Reinstalling Firefox is not a dependable first fix: it may keep the same profile and settings, and cannot correct an external VPN, proxy, antivirus, DNS, clock, or website problem.
7. Remove only the affected site’s stored data
Do this as a secondary step, especially if only one domain is affected. Ordinary cache clearing usually does not repair a connection that fails during TLS negotiation. Removing that site’s data may help if stale domain-specific data or an exception is involved, but it will not fix a network-level interruption.
Prefer deleting data for that domain rather than clearing everything. Mozilla warns that Forget About This Site can remove that domain’s history, cookies, passwords, cache, and exceptions; make sure you know your login details before using it: Mozilla support discussion of the feature.
8. Use Troubleshoot Mode to check for Firefox-specific causes
If the problem affects Firefox but not other browsers, try Firefox’s Troubleshoot Mode to see whether an extension or another customizable feature is involved. If the site works there, review extensions and Firefox customizations before returning to normal mode. A fresh profile can be a later diagnostic, but preserve important profile data and do not treat reinstalling as a cure for problems outside Firefox.
9. Try another network
Test using a different Wi-Fi network or a phone’s cellular hotspot. If the page works on the alternate connection, the original router, ISP, DNS provider, firewall, or network policy is a stronger suspect. On work, school, library, or government networks, do not remove required certificates, change proxy settings, or disable inspection without the network administrator’s approval.
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Try the site in another browser and on another network. If it fails everywhere, the website, its CDN, TLS configuration, a domain-specific filtering rule, or a route to the site may be responsible. A single Firefox error is not enough to conclude that the site’s certificate is invalid or that the server is at fault.
If the failure follows the site across browsers, devices, and networks, contact the site administrator and provide the exact error code, the affected URL, and the results of your comparisons. Some secure-connection errors do require a website owner to update server-side TLS support, but Mozilla discusses that outcome specifically for certain errors such as SSL_ERROR_UNSUPPORTED_VERSION; do not infer that diagnosis from PR_END_OF_FILE_ERROR alone.
If many websites fail
Prioritize components that affect multiple connections: VPN, DoH, proxy, security software, system time, and network policy. Change one setting at a time and retry the same page so you can identify which test changes the result. If the problem occurs only on a managed network, contact its IT administrator before changing required controls. If it occurs across networks but only in Firefox, Troubleshoot Mode or a carefully backed-up fresh profile can help distinguish a Firefox profile issue from an external one.
Quick Recap
When to contact someone else
- Website administrator: the failure follows one site across browsers, devices, or networks.
- VPN provider: the site works with the VPN disconnected but fails through multiple VPN servers, or the VPN’s web protection or DNS settings appear involved.
- Security-software vendor: the page works only when encrypted-traffic inspection is temporarily disabled.
- ISP or network administrator: multiple devices fail on one network, or a managed proxy, DNS filter, or TLS inspection policy may be involved.
Fixes to avoid
- Do not lower Firefox’s minimum TLS version, re-enable obsolete TLS versions, or change random
about:configsecurity preferences. - Do not bypass the warning or disable certificate checks; this error does not offer a safe general override.
- Do not delete Firefox certificate databases or custom certificates as a routine step. That can remove trust decisions and break access on managed networks.
- Do not disable all antivirus protection or your firewall to test a connection. Isolate encrypted-traffic inspection where possible and restore it after the test.
- Do not install third-party “SSL repair” utilities. They are not a substitute for finding whether the interruption comes from Firefox, local software, the network, or the website.
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