ERR_SSL_PROTOCOL_ERRORIssue When logged in to a ServiceNow instance the error ERR_SSL_PROTOCOL_ERROR is displayed. The issue may or may not be intermittent. The error message: ERR_SSL_PROTOCOL_ERROR is associated with the Chrome browser and is an indication the SSL connection can not be correctly established.CauseThis issue is mainly a client-side issue and could have (amongst others) one the following root causes: The end user's computer has an incorrect "system date and time" (on the end user's local computer or Citrix or Vm) leading to the certificate presented by the ServiceNow instance not being properly recognized as valid as Date and time are essential parts to check the certificate validity.The browser does not have the correct "TLS version" enabled leading up in the failing of the TLS handshake between the browser and the ServiceNow instance. ResolutionGenerally, this investigation should be conducted by the customer's Network/System administrators, however, ServiceNow support would need to ensure that in the case of "Custom URL" that a Valid Certificate is active within the F5. This can easily be checked by opening the "Custom URL" in a browser window and reviewing the Certificate by clicking on the lock icon in front of the URL Please note that in the case that a Certificate would read as "Incorrect or Invalid" when on the Tech support engineers browser, in a ServiceNow office that this issue is a Potential P1 Outage and should be logged as such. Checklist for fixing the ERR_SSL_PROTOCOL_ERROR Setting the correct Date & TimeIncorrect date & time settings might be causing trouble for you. Make sure that your system isn't lagging behind or running ahead.Why is this a problem? Certificate validity is an extremely important factor in the authentication process, and that means keeping very specific tabs on the time the certificate was signed and when it will expire. If there is an issue with your system's time and date, it can cause all kinds of problems during authentication. These browsers are designed to err on the side of caution, which is why something as simple as having the wrong time can cause an SSL connection error.Clearing Chrome's Browsing DataIf you already have the correct date & time, it's time to clear Chrome's cache and cookies. To do so, press Ctrl + Shift + Delete and erase your browsing data. Even if this hasn't fixed the "This site can't provide a secure connection" error, we recommend clearing your browsing data on a regular basis.Clearing your SSL StateIf neither of the above works, clearing your SSL State is the next thing you should try. Follow the steps below to do so: Go to Customize and control Google Chrome, the three dots you see just below the X (close) button.Click on Settings.Scroll down the page and open the Advanced Settings.Go to Open proxy settings by scrolling down or searching in the search bar. A window named 'Internet Properties' will open up. Go to the Content window and click on the Clear SSL State Button.Fix ERR_SSL_PROTOCOL_ERROR by disabling QUIC ProtocolQUIC (Quick UDP Internet Connections) provides a TLS/SSL equivalent connection to Google's servers. By default, the QUIC protocol is enabled in Chrome. To disable it, copy chrome://flags/#enable-quic and paste it into the address bar, hit enter. On top of your screen, the Experimental QUIC Protocol would have been set as Default. Disable it and relaunch Chrome.We don't necessarily advise this, but it's been proven to work in some obscure cases so we're putting it on the list. Checking your Antivirus SettingsWarning: This step isn't entirely safe as it allows the older, insecure SSL/TLS protocols that some of the websites still use.Antivirus software keeps an eye on the web pages you visit and protects you against any threats they may pose or contain. It does this by checking the SSL/TLS protocol a website uses. Upon finding the protocol to be unsafe and outdated, it prevents you from visiting the site.There isn't a single particular way to change the settings for all Antivirus software as the UI and settings differ from one software to another. You'd have to find and see if it's scanning the SSL protocols. If it does, disable it and see what happens. If the problem persists, revert to the original settings.Note: Generally, the reason you will see an antivirus program cause alarm about an SSL/TLS connection is that the server is attempting to negotiate a connection using a deprecated or vulnerable SSL or TLS versions such as SSL 3.0 or TLS 1.0. As we've written in similar advice articles, don't tamper with your antivirus or reduce your TLS version settings to accommodate a website's bad SSL/TLS configuration. The risks far outweigh the rewards.Enabling all SSL/TLS Versions – The Last ResortWarning: This step isn't entirely safe as it allows the older, insecure SSL/TLS protocols that some of the websites still use.When you visit an SSL-enabled website, it uses SSL/TLS protocols to communicate with the server. Sometimes, the SSL/TLS version of a website might not be compatible with your Chrome version as Chrome doesn't permit deprecated SSL/TLS protocols to run by default. Therefore, you'd need to change those SSL/TLS protocol settings. Here's how you can do it: Click on the three dots you see in the top-right corner of Chrome and click on Settings.Scroll down and go to Advanced Settings.Find the Proxy settings and open it.Click on AdvancedScroll down to the Security section comes up. Make sure that you have checked all SSL and TLS versions.Click Apply.Relaunch your Chrome.Note: Again, consider this suggestion entirely academic. The major browsers have all announced plans to disable support for all previous TLS versions, save TLS 1.2, and the recently-published TLS 1.3. This is being done for security reasons. Don't enable support for outmoded TLS and SSL versions with known vulnerabilities. No legitimate organization will ask you to compromise your browser's security settings to interact with its website.