When Mozilla Firefox displays the error code SSL_ERROR_NO_CYPHER_OVERLAP Firefox, it indicates that there is a discrepancy between the “cipher suite” that your browser and the server you are attempting to connect to. Although other popular browsers, such as Google Chrome, have their own warning messages to highlight the same issue, this exact error code is unique to the Mozilla Firefox browser.
There are a few simple steps you may take to address and remedy this issue. You may rapidly repair this mistake, though, if you have a deeper grasp of the contributing causes.
Keep reading and exploring to learn what the main causes and fixes are for the SSL error error_no_cypher_overlap error code in 2025.
Table of Contents
What is SSL_ERROR_NO_CYPHER_OVERLAP Firefox?
This error may occur due to server-side issues, old Firefox versions, or incorrectly configured SSL/TLS (Secure Socket Layer/Transport Layer Security) encryptions.
Different web browsers show multiple problems, but the SSL ERROR_NO_CYPHER_OVERLAP error is only seen by Firefox. The error name has been significantly modified to ERR_SSL_VERSION_OR CIPHER_MISMATCH in the Chrome browser.
This issue arises when the Firefox browser is unable to obtain the security information from the website you are attempting to visit, as it is web browser-related and pertains to SSL encryption security. This issue is typically caused by deactivated SSL/TLS certificates or expired SSL certificates.
Let us give you a quick overview of SSL encryption security and how it works before continuing. For site and data security, SSL digital certificates are put on websites. They use encryption to safeguard browser-server connections and keep unauthorized users from accessing site-sensitive information.
When the browser is unable to connect to the server, an SSL error occurs. When the site load attempt fails, Firefox will show the error code SSL_ERROR_NO_CYPHER_OVERLAP.
What Are The Main Reasons For The Error Code SSL_ERROR_NO_CYPER_OVERLAP?
It’s conceivable that Firefox may display the error message and the message “authenticity of the data cannot be verified.” If so, the notification can also suggest that you get in touch with the owner of the website. Though the website can be to blame, the problem might also be browser-related.
Following the installation of Cloudflare, some users have reported encountering this problem. Cloudflare’s SSL certificates employ the Server Name Indication (SNI) protocol, which is typically not supported by the browser.
Other main reasons include:
- Outdated Firefox browser: The error message appears because the most recent version of Firefox is not installed.
- Disabled SSL/TLS certificates: The error was caused by the browser disabling the SSL/TLS security certificate.
- Removal of RC4 (Rivest Cipher 4) support: RC4 is a stream cipher that is utilized in SSL/TLS certificates. The majority of browsers do not support the RC4 encryption since it is insecure. To create a secure connection, the browser and the server need to agree on a common encryption cipher. This error may occur if the browser’s RC4 support is removed.
Also Read: What is SSL VPN & How VPNs Can Boost Blog Security?
How To Fix SSL_ERROR_NO_CYPHER_OVERLAP Error?
To repair the problem code SSL_ERROR_NO_CYPHER, follow these steps, starting with the easiest remedy and getting progressively more complicated.
Update To The Most Recent Firefox Version
You should try to fix the problem code “SSL_ERROR_NO_CYPHER_OVERLAP” for the first time. I realize that just advising you to “update Firefox” seems cheesy, like the expert on the phone urging you to restart your device, but a new standard is likely in place that makes specific websites accessible, or that there is a new version of the cipher suites that are available. Getting the most recent version of the Firefox browser is usually a smart idea because there are additional advantages to not utilizing an older version, nonetheless.
Go to the Firefox settings, select the “General” tab, scroll down to the “Firefox Update” section, and click “Check for updates” as indicated above to update your Mozilla Firefox browser:
Getting the most recent version of Firefox from the official website is guaranteed when you use this method, which is also the simplest. Clear your page cookies, restart your web browser, and try again after updating Firefox. Go to step 2 if it doesn’t work.
Clear Your SSL3 And TLS Configuration
Resetting your TLS and SSL3 settings is the next thing you may attempt if upgrading Firefox didn’t work or if you’re using the most recent version. These protocols are necessary for certain websites to establish a connection. As a result, if yours are deactivated, the ” SSL_ERROR_NO_CYPHER_OVERLAP ” problem may be the cause.
Enter “about:config” in the website address bar of a new tab in your Firefox browser to reset them. A notice that reads, “This might void your warranty!” might appear. Alternatively, “Proceed with Caution“:
Firefox uses this warning to keep you from inadvertently altering important browser settings. To continue, click Accept the Risk.
In the search field on the following Advanced Preferences screen, enter “tls”:
By typing this, a list of all your TLS setups will be produced:
The values that are bolded are the ones that have changed recently, so look for those. To return any bolded values to their original settings, right-click on them and choose Reset.
Then, carry out the same procedure with SSL3. In the search bar, type “ssl3” and reset any recently modified values:
Additionally, confirm that the next two entries are set to false:
- dhe_rsa_aes_128_sha security
- dhe_rsa_aes_256_sha security
For security reasons, you must block these options.
Also Read: What is a Cipher Suite? Learn How SSL/TLS Ensures Data Protection
Verify If The Website is Accessible Using A Different Browser.
The next step is to determine if the issue is with the website you’re attempting to visit or with you. The simplest approach to accomplish this is to visit the website using a different browser. Try to access it on a different device, such as a smartphone, if possible. To guarantee a totally distinct device and network connection, it would be even better if you could turn off your smartphone’s Wi-Fi and utilize the network connection instead.
If you receive the same or a comparable SSL_ERROR_NO_CYPHER_OVERLAP error, it indicates that the server is the source of the problem rather than just your browser. If you are not the owner of the website, your only option is to message the owner and let them know about the issue. Even so, you might be able to get around the problem by using some of the other solutions listed below.
Lower The Version Of The TLS Fallback Limit
Thus far, we have only examined fixes that attempt to address possible issues and setups that could be the source of the error code SSL_ERROR_NO_CYPHER. There are a few things you can do, though, that can let you access the site at the cost of less security if you’re eager to go on it at any cost.
The following actions will affect the security of your browser. Therefore, you should undo them as soon as you can to allow you to access other websites without fear of dangerous websites or the theft of your private data.
Using your Firefox browser, navigate to “about:config” as before. After accepting the warning, enter “security.tls.version” in the search box as seen here:
Make the following adjustments in the list below:
- fallback-limit for security.tls => Put this at “0.”
- min for security.tls => Put this at “0.”
The purpose of these parameters is to set a floor on the versions of the cipher suite that the server and browser may agree upon. The modification mentioned above expands the range of values that the Firefox browser and server may agree upon, as receiving a SSL_ERROR_NO_CYPHER_OVERLAP error code indicates that they are unable to agree upon a cipher suite. At worst, they will agree on a protocol that isn’t secure but is low enough for both of them to embrace.
Permit Firefox To Display “Dangerous And Deceptive Content”
Since this step involves changing Firefox’s behavior to let through websites that it would normally block, it may be much riskier than the prior one. As previously mentioned, make sure to return this setting as quickly as you can.
Navigate to the Firefox settings page and, as indicated above, choose “Privacy & Security” from the left-hand menu:
Uncheck the first box under “Deceptive Content and Dangerous Software Protection,” as indicated above. The two boxes beneath will likewise become inactive if the main box is unchecked.
By doing this, Mozilla Firefox’s default settings for filtering harmful and misleading material will be removed.
Try to visit the website you were unable to access because of the “SSL_ERROR_NO_CYPHER OVERLAP” error after doing this. You may now be able to view the website if your browser blocked it because it was dangerous.
To reiterate, when you have finished using it, turn the setting back on! In general, circumventing browser security mechanisms is never a smart idea.
Conclusion
If the reasons or fixes are still working out, seeing SSL issues might become annoying. Finding the root of the issue and fixing it could take some time.
Thankfully, you can use this method to quickly and effectively fix the SSL_ERROR_NO_CYPHER_OVERLAP problem. It is never pleasant to be unable to access a website that you are attempting to visit. When the error message you are seeing is as perplexing as the SSL_ERROR_NO_CYPHER error, it may be quite annoying. Thankfully, there are a few easy measures you can take to fix this Firefox-related problem:
- Get the most recent version of the Firefox browser.
- Reset the SSL3 and TLS configurations.
- Get around your browser’s settings and security measures.
Comment below if you have any queries about this error or if you are still failing to resolve the issue in 2025.
FAQs (Frequently Asked Questions)
How To Fix Error Code SSL_ERROR_NO_CYPHER_OVERLAP In Firefox?
- Update To The Most Recent Firefox Version
- Clear Your SSL3 And TLS Configuration
- Verify If The Website Is Accessible Using A Different Browser.
- Lower The Version Of The TLS Fallback Limit
- Permit Firefox To Display “Dangerous And Deceptive Content”
What is SSL_ERROR_NO_CYPHER_OVERLAP?
When your browser cannot retrieve the security information for a website you are attempting to visit, you will see the “SSL_ERROR_NO_CYPHER_OVERLAP” message.
How To Bypass SSL_ERROR_NO_CYPHER_OVERLAP?
To resolve “SSL_ERROR_NO_CYPHER OVERLAP,” make sure the date and time on your computer are accurate, update your Firefox browser, and clear the cache.
How To Fix SSL Error In Firefox?
Try upgrading both your operating system and the browser to resolve SSL issues with Firefox. Verify the date and time on your computer and clear the cache and cookies in your browser.