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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Problem with ui/frame on getFragmentCallbacks","articleBody":"## Please, provide the details below:\r\nApplication crashes when navigating back on several views really fast and with the activityBackPressedEvent cancelling the back button on first view.\r\n\r\n### Did you verify this is a real problem by searching [Stack Overflow]\r\nYes, I've searched and couldn't find anything.\r\n\r\n### Tell us about the problem\r\nI've created an app with some views and I need to block the back button ONLY on the first view with the activityBackPressedEvent.\r\nBasically I've done this on the navigatedTo function of the first view:\r\n```\r\nmainPage = args.object;\r\nif(app.android) {\r\n      app.android.on(app.AndroidApplication.activityBackPressedEvent, backEvent);\r\n}\r\n\r\n```\r\nAnd on the backEvent function I've put:\r\n```\r\nfunction backEvent(args) {\r\n    var currentPage = frameModule.topmost().currentPage;\r\n    if(mainPage == currentPage)\r\n        args.cancel = true;\r\n}\r\n```\r\n\r\nBasically it works as expected except when I'm on view 5 and click several times on the back button, that's when the app crashes:\r\n![22091571_1647154951996162_1123662885_n](https://user-images.githubusercontent.com/16105597/30964532-a42a2d1e-a449-11e7-952d-35ede7e66a6e.png)\r\n\r\n### Which platform(s) does your issue occur on?\r\nAndroid\r\n\r\n### Please provide the following version numbers that your issue occurs with:\r\n- CLI: 3.2.1\r\n- Cross-platform modules: ~3.2.0\r\n- Runtime(s): 3.2.0\r\n\r\n### Please tell us how to recreate the issue in as much detail as possible.\r\nCreate some views and the navigation between them like View 1 --\u003e View 2 --\u003e View 3 --\u003e View 4 --\u003e View 5 and click on the back button really fast a lot of times. Also, insert the code I've put on the description of my problem in the code of first view.\r\n\r\n### Is there code involved? If so, please share the minimal amount of code needed to recreate the problem.\r\nAlready on the description of the problem.\r\n","author":{"url":"https://github.com/pedromareis","@type":"Person","name":"pedromareis"},"datePublished":"2017-09-28T11:41:15.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":15},"url":"https://github.com/4901/NativeScript/issues/4901"}