NotAllowedError

NotAllowedError is a type of DOMException used by web platform APIs to indicate that an operation is not allowed. It is typically raised when an action is blocked by user permission, policy, or the current context rather than by a technical fault. The error name is "NotAllowedError," and it appears in APIs such as MediaDevices.getUserMedia and Geolocation when access is denied, or when a required user gesture is not provided.

In practice, NotAllowedError often means the user has denied permission to use a resource (for example, the camera or microphone) or that the page is not allowed to perform a certain action under the current policy, such as autoplay restrictions. The exact conditions and messages can vary by API and browser, but the common theme is explicit denial or policy prohibition rather than a bug in the code.

Handling: Developers typically catch the DOMException and check the name property (error.name === "NotAllowedError"). The recommended response is to inform the user, request permission again in response to a clear user gesture, or degrade gracefully if access cannot be granted. It can also be helpful to check permission status via the Permissions API and ensure the page is served over HTTPS.

Compatibility: NotAllowedError is widely supported in modern browsers for the relevant APIs. Some older environments may report similar conditions under different error names. Related errors include NotReadableError, NotSupportedError, and SecurityError.