MediaDevices.getUserMedia() - Web APIs
if the user denies permission, or matching media is not available, then the promise is rejected with notallowederror or notfounderror respectively.
...if the browser cannot find all media tracks with the specified types that meet the constraints given, then the returned promise is rejected with notfounderror.
... notfounderror no media tracks of the type specified were found that satisfy the given constraints.

Node.removeChild() - Web APIs
l also happen if child was in fact a child of element at the time of the call, but was removed by an event handler invoked in the course of trying to remove the element (e.g., blur.) errors thrown the method throws an exception in 2 different ways: if the child was in fact a child of element and so existing on the dom, but was removed the method throws the following exception: uncaught notfounderror: failed to execute 'removechild' on 'node': the node to be removed is not a child of this node.
... = document.getelementbyid("top"); while (element.firstchild) { element.removechild(element.firstchild); } causing a typeerror <!--sample html code--> <div id="top"> </div> <script type="text/javascript"> let top = document.getelementbyid("top"); let nested = document.getelementbyid("nested"); // throws uncaught typeerror let garbage = top.removechild(nested); </script> causing a notfounderror <!--sample html code--> <div id="top"> <div id="nested"></div> </div> <script type="text/javascript"> let top = document.getelementbyid("top"); let nested = document.getelementbyid("nested"); // this first call correctly removes the node let garbage = top.removechild(nested); // throws uncaught notfounderror garbage = top.removechild(nested); </script> specifications ...

Bluetooth.requestDevice() - Web APIs
notfounderror there is no bluetooth device that matches the specified options.

DOMError - Web APIs
notfounderror the object can not be found here.

DOMException - Web APIs
(legacy code value: 7 and legacy constant name: no_modification_allowed_err) notfounderror the object cannot be found here.

FileReaderSync.readAsArrayBuffer() - Web APIs
exceptions the following exceptions can be raised by this method: notfounderror is raised when the resource represented by the dom file or blob cannot be found, e.g.

FileReaderSync.readAsBinaryString() - Web APIs
exceptions the following exceptions can be raised by this method: notfounderror is raised when the resource represented by the dom file or blob cannot be found, e.g.

FileReaderSync.readAsDataURL() - Web APIs
exceptions the following exceptions can be raised by this method: notfounderror is raised when the resource represented by the dom file or blob cannot be found, e.g.

FileReaderSync.readAsText() - Web APIs
exceptions the following exceptions can be raised by this method: notfounderror is raised when the resource represented by the dom file or blob cannot be found, e.g.

HTMLFormElement.requestSubmit() - Web APIs
notfounderror the specified submitter isn't a member of the form on which requestsubmit() was called.

IDBDatabase.deleteObjectStore() - Web APIs
has been deleted or removed.) in firefox previous to version 41, an invalidstateerror was raised in this case as well, which was misleading; this has now been fixed (see bug 1176165.) notfounderror you are trying to delete an object store that does not exist.

IDBDatabase.transaction() - Web APIs
notfounderror an object store specified in in the storenames parameter has been deleted or removed.

IDBObjectStore.deleteIndex() - Web APIs
has been deleted or removed.) in firefox previous to version 41, an invalidstateerror was raised in this case as well, which was misleading; this has now been fixed (see bug 1176165.) notfounderror occurs if there is no index with the given name (case-sensitive) in the database.

IDBObjectStore.index() - Web APIs
notfounderror there is no index with the given name (case-sensitive) in the database.

IDBTransaction.objectStore() - Web APIs
exceptions this method may raise a domexception of one of the following types: exception description notfounderror the requested object store is not in this transaction's scope.