As the answer of Vu Nguyen is somewhat correct, but in fact it does not explain other scenarios where this can happen, I will share my decision on this issue. For me, the problem arose when I upgraded to Onsen UI 1.3.0 from 1.1.4, and the point where I got this error was on navigator.pushPage('page1.html') , where page1.html looked like this:
<ons-template id="page1.html"> <ons-sliding-menu menu-page="menu.html" main-page="browse.html" side="left"> </ons-sliding-menu> </ons-template>
Now, the Onsen user interface cannot find the on-page page, which for some reason is not needed before. So the solution is to wrap the menu of the ons-sliding menu on the ons page, like this
<ons-template id="page1.html"> <ons-page> <ons-sliding-menu menu-page="menu.html" main-page="browse.html" side="left"> </ons-sliding-menu> </ons-page> </ons-template>
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