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Fix SSL_ERROR_NO_CYPHER_OVERLAP in Mozilla Firefox

Resolve Firefox SSL cypher overlap errors to access outdated or secure sites.

FirefoxSSLSecurityError

Confirmed working on: Windows 10 · Windows 11 · macOS · Linux

Before you begin

Match the environmentUse this guide only for Windows 10, Windows 11, macOS, Linux or a clearly compatible setup.
Protect recoveryBack up important data and save encryption or account recovery keys before changing system state.
Know when to stopMake one change at a time and stop if the result differs from what the guide describes.

Problem overview

The SSL_ERROR_NO_CYPHER_OVERLAP error occurs when Firefox cannot securely connect to a website because the site uses an outdated encryption protocol. Firefox blocks the connection to protect your data.

Common causes

  • The website uses an old, unsupported TLS version (TLS 1.0 or 1.1)
  • Antivirus software is intercepting and breaking SSL connections
  • Firefox is not up to date
  • Corrupted Firefox profile settings

Solution 1: Enable older TLS versions

You can temporarily configure Firefox to accept older TLS connections if you must access an outdated site.

  1. Open Firefox, type about:config in the address bar, and press Enter.
  2. Click Accept the Risk and Continue.
  3. Search for security.tls.version.min.
  4. Double-click the preference and change its value to 1 (which allows TLS 1.0).
  5. Reload the website.
Caution

Lowering the minimum TLS version reduces your browser’s security. Remember to change the value back to 3 (TLS 1.2) when you finish using the site.

Solution 2: Disable antivirus SSL scanning

Some antivirus programs scan encrypted traffic and inadvertently cause SSL protocol errors.

  1. Open your antivirus or internet security suite.
  2. Navigate to Settings or Preferences.
  3. Look for a setting named Web Shield, HTTPS Scanning, or SSL Scanning.
  4. Disable this feature temporarily.
  5. Restart Firefox and test the connection.

Solution 3: Update Firefox

Ensure you are running the latest version of Firefox, which may contain fixes for SSL handling.

  1. Open Firefox and click the menu button (three horizontal lines).
  2. Click Help, then select About Firefox.
  3. Firefox will automatically check for updates and download them.
  4. Click Restart to update Firefox if an update was installed.

Confirm the result

  1. Repeat the exact action that originally triggered the problem.
  2. Confirm the original error or symptom is gone and no new warning has appeared.
  3. If the guide changed a driver, service, package, or system setting, restart once and test again.
  4. If the result is worse or unexpected, stop. Reverse only the last change using its documented restore option; if none is documented, use your backup or qualified support.

Questions about this fix

Is it safe to bypass SSL warnings?

Only bypass SSL warnings if you trust the site completely, as it may lack modern encryption.

Why does only Firefox show this error?

Firefox enforces strict modern security protocols and drops support for outdated TLS versions sooner than some other browsers.

Did this fix work for you?

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