The ERR_UNKNOWN_URL_SCHEME error is typically caused by a browser issue where there is no application on the device capable of handling a specific action related to the URL scheme. It has been identified as a bug in the Chromium browser ( Chromium bug ). Specifically, in Chrome versions 40 and above, this bug reoccurs when manually entering the URL of the redirect page in the address bar. The issue has been reported on the Chromium issue tracker for further investigation and resolution. The issue is on the chromium issue tracker here .

The ERR_UNKNOWN_URL_SCHEME error may occur while attempting to open another page of the interface. A temporary solution for this issue is to navigate backward and then attempt to open the page again. This action can sometimes help to temporarily bypass the err_unknown_url_scheme error on Chrome and Android devices, allowing you to access the desired page. However, please note that this solution may only provide a temporary workaround and may not completely resolve the underlying cause of the error. Further investigation and troubleshooting may be required to address the issue permanently.

You may get this "ERR_UNKNOWN_URL_SCHEME error" during mailto: or tel: links inside an iframe.

To solve it, try to add target="_blank" in your URL Scheme/Code.


The ERR_UNKNOWN_URL_SCHEME error currently lacks a specific and definitive solution. Both Android and PC users encounter this error, indicating the need for further investigation and resolution. Chromium has a long-standing bug related to the handling of links without protocols, which occasionally receives patches but tends to resurface. As a possible workaround, you can try prefixing your links with "http://" or "https://" to potentially resolve the issue. However, it is essential to keep in mind that this may not be a universal fix and that a more comprehensive solution may be required to fully address the problem.


What is URL Scheme

URL Scheme refers to the method of interpreting the part of a URL that comes after the colon (:). For example, the "app:" URL scheme is used by packaged applications to access resources within a container, which can then be utilized with web platform features accepting URLs. URL schemes, like "http://..." or "ftp://...", enable users to open apps from other applications. The power of URL schemes lies in their capacity to perform specific actions as an app is opened. Each scheme represents a distinct addressing system, with the part preceding the colon identifying the scheme in use, and the part after the colon following a syntax unique to that scheme. The flexibility of URL schemes allows for seamless extension and incorporation of new schemes, making the URL standard highly adaptable and expandable.

It is challenging to generalize schemes as they can vary significantly. While some schemes may have names corresponding to protocols used for resource fetching, such as "http," "https," or "ftp," this is not a strict rule. For instance, the "mailto" scheme denotes an e-mail address but does not necessarily imply a particular protocol for retrieval. Additionally, some schemes do not align with any specific protocol. An example is the "about" scheme utilized in web browsers, where the resource is not fetched through any protocol but is instead built into the client itself. The diversity of schemes allows for versatility in defining how different resources are accessed and utilized across various applications and platforms.


The ERR_UNKNOWN_URL_SCHEME error occurs when encountering an unrecognized URL scheme, indicating that the protocol or addressing method in the URL is not supported. This error commonly arises in web browsers and may be temporarily resolved by adding a valid protocol prefix, such as "http://" or "https://", to the URL. However, the error's root cause may require further investigation and bug fixes in the browser's handling of URL schemes.