How to Fix PR_END_OF_FILE_ERROR in Firefox?

Mozilla Firefox is one of the most used browsers worldwide. As of 2024, more than 362 million users are using it to browse the Internet.

The reason for doing so is quite simple – Mozilla Firefox is not only safe to use, but it also keeps your data and private information safe from malicious actors. But as with any other web browser, Firefox can also encounter infrequent errors. One of such errors that pops up in the Firefox browser is the – PR_END_OF_FILE_ERROR.

The PR_END_OF_FILE error is a troublesome and frustrating error that’s specific to the Firefox browser. It is different from other secure connection errors that you might have faced in different browsers, like – Google Chrome, Internet Explorer, etc. The pr_end_of_file warning message generally pops up due to external programs, such as third party software or due to an incorrect browser configuration.

In this piece, we will explore the pr_end_of_file_error in great depth, as in – What exactly is this error? What are the reasons because of which this error pops up? And then the most important part – “How to fix the pr_end_of_file_error?” If you are one of those person who is being greeted by the error in discussion and don’t know how to get it fixed, don’t worry and read the article till the end. The methods or techniques listed in the article have been tested by our expert team, and we are sure that one of these will surely make the error go away.

What is the PR_END_OF_FILE Error?

The pr_end_of_file is an error that occurs on the client side and pops up in Mozilla Firefox when the browser is unable to form a secure and encrypted connection with the site that the user was trying to access. The browser is unable to form a connection as it wasn’t able to find a compatible cipher suite. Cipher suites are instructions for verifying and securing network connections using cryptographic protocols.

Also Read: What is a Cipher? Types of Ciphers in Cryptography

When the client (browser) tries to connect to the site by creating a Secure Socket Layer connection, it (Firefox) passes through a sequence of cipher suites. The browser browses through the cipher suite list, and if it can connect to an appropriate cipher suite, the connection is established.

But if it isn’t able to find an appropriate suite even after browsing the whole cipher suite list, then after reaching the end of the cipher suite list, it returns the Secure Connection Failed PR_END_OF_FILE_ERROR.

What Are the Reasons

The main reason that the pr_end_of_file_error pops up is that the Firefox browser is unable to find a suitable cipher suite to connect to, even after browsing the while cipher suite list.

Apart from that, other reasons are:

Change in Mozilla Firefox browser SSL Settings:

If the user changes the Firefox browser’s SSL settings, then in that case, the cipher variants that were earlier being used by the browser will no longer be supported and will become incompatible with the browser.

Interference from Proxy or VPN Services:

Users often use proxy or VPN services to hide their IP addresses and remain anonymous on the Internet. But sometimes, these services can interrupt the establishment of a secure and encrypted connection, which may give rise to the pr_end_of_file error. 

Interference from 3rd Party Applications:

Many of us use third-party software or applications, such as antivirus software, firewalls, etc. But sometimes, these network and security applications can interrupt the SSL handshake process by trying to alter or scan the encrypted data. This can also be the reason why the error is occurring.  

Compromised Firefox Browser Profile:

Synchronization issues between the Firefox mobile and desktop versions can compromise or corrupt the Mozilla Firefox profile, ultimately leading to the pr_end_of_file_error.

How to Fix PR_END_OF_FILE_ERROR?

Five techniques can be applied to fix the pr_end_of_file_error. Start with the first method listed. If it does not work for you, move on to the subsequent (next) one.

• Turn Off Domain Name System over HTTPS Protocol
• Temporarily Disable VPN & Proxy (if in use)
• Reset Mozilla Firefox Browser’s SSL Settings
• Temporarily Disable 3^rd Party Security Software (if in use)
• Create a New Mozilla Firefox Profile

Let’s explore each of these methods in detail.

Turn Off Domain Name System over HTTPS Protocol

Domain Name System over HTTPS, a.k.a. DoH is a protocol. It shields the DNS traffic from malicious actors by encrypting it. But sometimes, when this protocol is enabled, it causes various issues that can give rise to connection errors, just like the one we are discussing right now. Hence, if the DoH protocol is enabled, turn it off.

Follow the steps mentioned below to turn off the DoH protocol:

• Open a fresh tab in Mozilla Firefox.
• In the URL (address) bar, type about:config.
• Press Enter.
• The Advanced Preference page will appear.
• On the Advanced Preferences page, click Accept the Risk and Continue button.
• A new search bar will appear.
• In the search bar, type network.trr.mode.
• Double-click the digit 2 (two).
• Press 0 (zero) on the keyboard.
• Press Enter.
• Restart the Mozilla Firefox browser.
• Verify whether the issue still exists or not.

Temporarily Disable VPN & Proxy (if in use)

“N” number of people use proxy or VPN (virtual private network) to remain anonymous on the Internet by hiding their IP address. But sometimes, these services even block secure and encrypted connections.

When this happens, Firefox is unable to find a suitable or appropriate cipher suite and ultimately pops up this warning message. Hence, if you are using any of these services, temporarily deactivate them and, once done, re-access the site.

Follow the steps mentioned below to disable a proxy:

• Open a fresh tab in Mozilla Firefox.
• Click Open application menu (three horizontal lines) icon, placed on the top right position.
• From the list, click Settings.
• The Settings page will appear.
• Scroll down.
• Under the Network Setting section, click Settings.
• The Connection Settings dialogue box will appear.
• Under the Configure Proxy Access to the Internet section, check the radio button placed adjacent to the No proxy option.
• Click OK.
• Restart the Mozilla Firefox browser.
• Verify whether the issue still exists or not.

Follow the steps mentioned below to disable VPN:

• Click Search, placed on the taskbar.
• Type VPN and press Enter.
• The Network & internet > VPN page will appear.
• Click the Disconnect button placed adjacent to the VPN name.
• Restart the Mozilla Firefox browser.
• Verify whether the issue still exists or not.

Reset Mozilla Firefox Browser’s SSL Settings

If you have changed the Mozilla Firefox browser’s SSL settings, then it’s possible that due to those changes, the Firefox browser is showing the pr_end_of_file warning message. If, at any time, you have made changes in the settings, switch them back or simply reset them to their default state. Once done, verify whether the error disappears or not.

Follow the steps mentioned below to reset Mozilla Firefox browser’s SSL settings:

• Open a fresh tab in Mozilla Firefox.
• Click Open application menu (three horizontal lines) icon, placed on the top right position.
• From the list, click Help.
• From the list, click More troubleshooting information.
• The Troubleshooting Information page will appear.
• On the Troubleshooting Information page, under Give Firefox a tune up section, click Refresh Firefox.
• The Refresh Firefox to its default settings dialogue box will appear.
• In the Refresh Firefox to its default settings dialogue box, click Refresh Firefox.
• Wait for a min until a new Firefox tab opens.
• Re-access the site.
• Verify whether the issue still persists or not.

Temporarily Disable 3^rd Party Security Software (if in use)

Third-party security software, like antivirus, firewall, etc., shields your system from malicious codes or malware. But, sometimes, to protect the system, they disrupt the SSL handshake process, which is vital for establishing a secure and encrypted connection. And when it happens, the Firefox browser pops up the PR End of File warning message.

Follow the steps mentioned below to temporarily disable antivirus:

• Click Search, placed on the taskbar.
• Type Windows Security and press Enter.
• The Windows Security window will open.
• The Virus & threat protection page will open.
• Under the Virus & threat protection settings section, click the Manage settings option.
• Under the Real-time protection section, use the toggle switch to deactivate it.
• The User Account Control window will open.
• Click Yes in the User Account Control window.
• Click Search, placed on the taskbar.
• Type Firefox and press Enter.
• A new Firefox tab will appear.
• Re-access the site.
• Verify whether the issue persists or not.

Follow the steps mentioned below to temporarily disable firewall:

• Click Search, placed on the taskbar.
• Type Windows Defender Firewall and press Enter.
• The Windows Defender Firewall window will appear.
• In the Windows Defender Firewall window, in the left pane, click Turn Windows Defender Firewall on or off.
• Under the Private network settings section, check the checkbox placed adjacent to the Turn off Windows Defender Firewall (not recommended) option.
• Click OK.
• Click Search, placed on the taskbar.
• Type Firefox and press Enter.
• A new Firefox tab will appear.
• Re-access the site.
• Verify whether the issue persists or not.

Create a New Mozilla Firefox Profile

If none of the above methods have worked for you and the issue still persists, then you should create a new Mozilla Firefox profile. This is so because a corrupted or misconfigured Firefox profile can give rise this. Hence, create a new one.

Follow the steps mentioned below create a new Mozilla Firefox profile:

• Close all the Mozilla Firefox tabs.
• Click Windows + R keys simultaneously on the keyboard.
• The Run dialogue box will appear.
• In the Open filed, type firefox.exe –P.
• Press Enter.
• The Firefox – Choose User Profile dialogue box will appear.
• In the Firefox – Choose User Profile dialogue box, click Create Profile.
• Click Next.
• The Create Profile Wizard will appear.
• In the Enter new profile name field, type a name of your choice.
• Click Next.
• Verify the new profile is selected and click Start Firefox.
• Re-access the site.
• Verify whether the issue persists or not.