The “ERR_UNKNOWN_URL_SCHEME” is an error message that Google released with the 40th version of Chrome on the 21st of January 2015. It appears when you type in an address with a protocol that Google doesn’t support. Other browsers like Firefox and Edge also have their own version of this error, but the particular error code “ERR_UNKNOWN_URL_SCHEME” is unique to Chrome. Here are some common causes of the error and what you can do to fix it.
- Misspellings Normally Cause The ERR_UNKNOWN_URL_SCHEME Error
- Google Often Doesn’t Even Show The ERR_UNKNOWN_URL_SCHEME Error
- Browser Settings Or Extensions Can Cause The ERR_UNKNOWN_URL_SCHEME Error
- Make Sure you Have the Latest Version of Your Browser
- Use Alternative Programs to Open the Mismatched Protocols
- Reset your Browser Settings
- Firefox and Edge Provide Different Error Messages
- Bottom Line: You’re Unlikely to Encounter this Error
Misspellings Normally Cause The ERR_UNKNOWN_URL_SCHEME Error
Most of the time, you simply type in the protocol incorrectly. For example, missing a double slash (//) and adding an extra “p” to “http” or “https” causes the overwhelmingly large majority of “the “ERR_UNKNOWN_URL_SCHEME” errors.
Here are some common misspellings that often generate it:
- “htttp” or “httpp” instead of “http”
- “hhtps” or “hps” instead of “https”
- “htps” instead of “https”
- “http://” instead of “http://” (missing the colon and double slashes)
- “https//” instead of “https://” (missing the colon after “https”)
- “http//” instead of “http://” (missing the colon after “http”)
- “htts” instead of “https”
- “httpss” instead of “https”
As you can see, these are trivial examples that we all make from time to time. In fact, some of these URLs look so similar to the original that our eyes can easily deceive us and we won’t even realize we made a mistake – often even while looking for such mistakes. I’ve done it myself many times. While typing in the protocol for a site, I often forget to include the colon, and it can take a few seconds before I figure out what I did wrong.
So if you encounter the “ERR_UNKNOWN_URL_SCHEME” error, check your spelling first.
Google Often Doesn’t Even Show The ERR_UNKNOWN_URL_SCHEME Error
Modern browsers are loathe to show error messages to users, no matter how informative. When they encounter an error like the one above, they simply redirect it to a search instead of trying to open a protocol they don’t recognize. For example, here’s the output of Chrome when I “accidentally” type in the wrong protocol:
I’ve tested the same thing in other browsers like Firefox and Edge, and they don’t show me the error, either. So going forward, I suspect that you won’t be seeing much of this error anymore. After all, a search result is usually a better option than showing this error message, and chances are that the top result will show you the site that you intended to go to in the first place.
Browser Settings Or Extensions Can Cause The ERR_UNKNOWN_URL_SCHEME Error
You must have noticed that when you click on a “mailto:” link, your browser asks you to choose the application using which you want to open the link. Or if you’ve already configured your mail application as the default, then your browser opens the link in your chosen app – I use Mailbird, so that’s what the link opens on my PC.
However, sometimes your operating system doesn’t recognize the protocol used, and the browser might throw this error if the protocol isn’t supported. While I don’t have any specific examples, your Google Chrome extensions might also cause this problem if they interfere with the normal workings of the protocol chain. So a good place to start with debugging the “mailto:”ERR_UNKNOWN_URL_SCHEME” error is to disable all your extensions on Google Chrome and then see if the page or application that you’re trying to reach works. If it goes through, start enabling all your extensions one by one until you find the one causing the problem, and then decide how you want to deal with it.
Make Sure you Have the Latest Version of Your Browser
If you’re sure that you haven’t misspelled your protocol, you should check whether or not you’ve fully updated your browser. This can slip under the radar, as most browsers update themselves in the background, but if your update gets stuck for some reason, it might cause the ERR_UNKNOWN_URL_SCHEME error.
For Chrome, go to Settings and click the “About Chrome” link on the bottom left of the settings page and it will immediately check to see if you have the latest version as shown here:
On Firefox, you need to click the “Help” link in the menu and choose “About Firefox” as shown here:
This will show you the dialog box with the latest Firefox update and an option to restart the browser if it has already downloaded an update. For Microsoft Edge, you can find it in the “About Microsoft Edge” list in the settings.
So ensure your browser is up-to-date, which might fix the “ERR_UNKNOWN_URL_SCHEME” error.
Use Alternative Programs to Open the Mismatched Protocols
If your browser refuses to open a certain type of link, you might consider using a program that uses it directly. Take magnet links, for example. Here’s what a magnet link looks like:
I tried pasting the above link into various browsers, but they all directed me to a search page. I must install a torrent application that will make sense of this protocol. Without such a program, my browser doesn’t know what to do with it and just does an ordinary search.
But if you want to open this link without a browser, then you can download a torrent application on your own and paste it into the search bar, which will take you to the torrent you want. This is how you can use a 3rd party program to open a URL that your browser won’t open for you.
Another example is mail links. Most PCs already have some default mail client, even if you don’t use it. But if your system is missing a mail client entirely, then you can simply install one and if it registers for the “mailto” links, then the next time you try and use a URL like that, your browser will redirect the request to the relevant program.
Reset your Browser Settings
Browsers are complicated pieces of software, and you never know when something settings-wise might be messed up, or if you accidentally changed something. If you’re stuck and need to troubleshoot the “ERR_UNKNOWN_URL_SCHEME” error, you should consider resetting your browser to its default settings. To do this in Chrome, open the settings and click “Reset Settings”. You should see a dialog box like this:
Click “Reset settings” and you’re done! Firefox and Edge have their own “reset settings” page, so it should be easy to repeat the procedure.
Firefox and Edge Provide Different Error Messages
The error “ERR_UNKNOWN_URL_SCHEME” is unique to Chrome, so you won’t see it on other browsers. However, each has its own error message for the same problem. For example, on Microsoft Edge, the error message reads:
Can't reach this page. The scheme of this URL isn't supported.
While on Firefox, it says:
Firefox doesn’t know how to open this address
In either case, it means the same thing.
Bottom Line: You’re Unlikely to Encounter this Error
The “ERR_UNKNOWN_URL_SCHEME” has almost vanished these days because browsers now redirect you to a search page when you type in a URL that doesn’t make sense. In a way, this is a good thing because by itself, it’s meaningless to most people. Nonetheless, if you do encounter this error, check you spelling, reset your browser settings, and in the worst case, install a program that specifically handles that particular URL.
I’m a NameHero team member, and an expert on WordPress and web hosting. I’ve been in this industry since 2008. I’ve also developed apps on Android and have written extensive tutorials on managing Linux servers. You can contact me on my website WP-Tweaks.com!