The sec_error_reused_issuer_and_serial is an indication that a certificate that is already present on the system is being reused by another server/IP. This warning may come either due to user end issues on the server-related problems. It is not possible to cover the server-related errors in detail (some suggestions are discussed at the end of the article) but on the user end, this behavior is mainly caused by:
Try Another Browser
The sec_error_reused_issuer could be a result of a temporary issue with the browser in use (e.g., Firefox), and using another browser may solve the problem. Before proceeding, check if relaunching the problematic browser clears out the error. If you are using the Chrome browser, then before trying another browser, check if typing thisisunsafe (without clicking on any links) on the error page lets you access the website.
Delete the Problematic Certificate from the Application
If a certificate is already having an exception in a browser or application’s database and a similar certificate (with the same serial number) is served by a website, then the application (like Outlook) or browser may throw the Sec_Error_Reused_Issuer_And_Serial error. In such a case, deleting the old exception for the certificate in the application or browser’s certificate manager may solve the problem. Waring: Proceed at your own risk as an attack (especially, MITM attack) on the system/network may cause similar symptoms and, in that case, deleting the certificate can harm the system, data, or network.
Delete the Problematic Certificate in the Firefox
If the issue is not limited to a particular website but is caused by the router, then check if deleting the router certificates (like the Netgear server certificates) in the browser solves the problem.
Delete the Problematic Certificate for An Email Application
Delete the Certificate File from the AppData directory of the Browser
If the certificate file got corrupted and not shown in the browser’s certificate tab, then deleting the file from its location in the AppData directory of the browser (e.g., Firefox) may solve the problem. In the case of a Mac, you may execute the following in the Terminal and relaunch Firefox to solve the security error:
Clear the Browser Cache
Browsers tend to create a cache of frequently used web content and if the browser’s cache is corrupt or a similar certificate is present in the browser’s cache, then the browser may throw sec_error_reused_issuer_and_serial error. In this context, clearing the browser’s cache may solve the problem.
For Firefox
For Chrome
Restore the Browser to the Factory Defaults
A mere misconfiguration of browser settings may cause the sec_error under discussion and restoring the browser to the factory defaults may solve the problem. Keep in mind a misconfiguration of one browser may trigger the behavior on other browsers, so, you may have to restore all the browsers on the system to the factory defaults. Before proceeding, make sure to back up the essential data/info
Firefox
Chrome
Edge
Internet Explorer
Keep in mind that Internet Explorer manages many of the Internet settings on a Windows PC and its misconfiguration may impact all the browsers on the system. Here, resetting the Internet Explorer may solve the problem. If not and the issue started after a browser update, then check if rolling back the browser update or installing an older version of the browser solves the problem.
Disabling SSL Filtering of the Security Software or Uninstall it
If the security suite of the PC (Kasperksy and ESET are reported to cause the issue) is interfering with the network packets in a way that triggers the browser security, then the browser may show the sec_error_reused_issuer_and_serial. In this context, disabling SSL protocol filtering of the security software or uninstalling it may solve the problem. Warning: Proceed at your own risk as editing the security product (antivirus, firewall, antimalware, etc.) settings may expose the system, data, or network to threats.
Disable SSL Protocol Filtering of the Security Product
Uninstall the Security Product of Your System
Try Another Network
The sec_error_reused_issuer problem could be a result of a temporary issue with the router or current network. In such a case, trying another network may let a user access the problematic websites. If the issue was resolved with another network, make sure the flood protection mechanism of the router (LAN ping flood protection or Security > Attack Checks > Block UDP Flood) is not triggering the issue. If that did not work, then check if resetting the router to the factory defaults solves the problem. If that did not work, check if changing the device binding in the following router settings solves the problem: If the issue occurred after a router firmware upgrade, check if downgrading the router firmware solves the problem.
Suggestions For Server-related Issues:
Until now, we tried to cover the issue from a user’s point of view but for server-related issues, you may try the following suggestions reported by users to solve the problem as it is practically impossible to cover all the scenarios on a server causing the issue.
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