# Kibana 6.1.1 Fatal Error at start **URL:** \ **Category:** Kibana\ **Created:** [December 22, 2017, 11:01am UTC](https://discuss.elastic.co/t/kibana-6-1-1-fatal-error-at-start/112986 "2017-12-22T11:01:26Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![fragatina](https://avatars.discourse-cdn.com/v4/letter/f/ccd318/32.png) [@fragatina](https://discuss.elastic.co/u/fragatina)\ **Post date:** [December 22, 2017, 11:01am UTC](https://discuss.elastic.co/t/kibana-6-1-1-fatal-error-at-start/112986/1 "2017-12-22T11:01:26Z")
I've updated to latest Elasticsearch/Kibana to 6.1.1 and go the following Fatal error in Kibana (which prevents to display anything else besides the following error in the browser). I don't have any customized plugins installed. " TypeError: undefined is not an object (evaluating 'Observable\_1.Observable.prototype') (http://\:5601/bundles/kibana.bundle.js?v=16350:112) Version: 6.1.1 Build: 16350 Error: TypeError: undefined is not an object (evaluating 'Observable\_1.Observable.prototype') (http://\:5601/bundles/kibana.bundle.js?v=16350:112) onerror@http://\:5601/bundles/commons.bundle.js?v=16350:45:8737 " It used to work fine with 6.0.0 version ---
**Author:** ![Mojster](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/mojster/32/21209_2.png) [@Mojster](https://discuss.elastic.co/u/Mojster)\ **Post date:** [December 22, 2017, 12:41pm UTC](https://discuss.elastic.co/t/kibana-6-1-1-fatal-error-at-start/112986/2 "2017-12-22T12:41:58Z")
I've got similar issue with 6.1.0 & 6.1.1, but mine's with `react` and not `prototype`. You can read here: [Kibana 6.1.0. starts with error](https://discuss.elastic.co/t/kibana-6-1-0-starts-with-error/111754) Try deleting optimeze folder. It did help in one case. ---
**Author:** ![fragatina](https://avatars.discourse-cdn.com/v4/letter/f/ccd318/32.png) [@fragatina](https://discuss.elastic.co/u/fragatina)\ **Post date:** [December 22, 2017, 2:21pm UTC](https://discuss.elastic.co/t/kibana-6-1-1-fatal-error-at-start/112986/3 "2017-12-22T14:21:56Z")
Thanks Mojster, removing the .cache on the optimize folder didn't help with me either (I have the same error). Nor removing the optimize folder (with this kibana fails to load). I've use safari 11.0 in mac. In chrome 62.0 (also for mac), I get the same error as you with prototype: '' Uncaught TypeError: Cannot read property 'prototype' of undefined (http://\:5601/bundles/kibana.bundle.js?v=16350:112) Version: 6.1.1 Build: 16350 Error: Uncaught TypeError: Cannot read property 'prototype' of undefined (http://\:5601/bundles/kibana.bundle.js?v=16350:112) at window.onerror (http://\:5601/bundles/commons.bundle.js?v=16350:45:8728) " ---
**Author:** ![tsullivan](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/tsullivan/32/31077_2.png) [@tsullivan](https://discuss.elastic.co/u/tsullivan)\ **Post date:** [December 26, 2017, 10:26pm UTC](https://discuss.elastic.co/t/kibana-6-1-1-fatal-error-at-start/112986/4 "2017-12-26T22:26:43Z")
Hi @fragatina , I see that you wrote you "don't have any custom plugins installed," but do you have any standard plugins like X-Pack? If so, try uninstalling and re-installing the plugins that you have. ---
**Author:** ![Gourav\_Kumar](https://avatars.discourse-cdn.com/v4/letter/g/c68b51/32.png) [@Gourav\_Kumar](https://discuss.elastic.co/u/Gourav_Kumar)\ **Post date:** [December 28, 2017, 10:18am UTC](https://discuss.elastic.co/t/kibana-6-1-1-fatal-error-at-start/112986/5 "2017-12-28T10:18:54Z")
Do we have a solution for the above issue? Even I am getting the same error on opening Kibana. Any suggestion would be much appreciated. OS :- Windows 2012 R2 64 bit. Kibana: 6.1.1 ![image](https://us1.discourse-cdn.com/elastic/original/3X/5/9/59e7bd4f94d1f5e5f9c379e450e3de2224936274.png) ---
**Author:** ![Winfield\_Henry](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/winfield_henry/32/69344_2.png) [@Winfield\_Henry](https://discuss.elastic.co/u/Winfield_Henry)\ **Post date:** [December 31, 2017, 10:16pm UTC](https://discuss.elastic.co/t/kibana-6-1-1-fatal-error-at-start/112986/6 "2017-12-31T22:16:21Z")
Hello, Same issue here. 64bit Windows 10 ES 6.1.1 KB 6.1.1 and 6.1.0 have similar isssue: "Uncaught TypeError: (0 , \_reactcss.handleHover)" No plugins installed. This was a completely new from .zip installation of ES and KB. KB 6.1.0 produces same error KB 6.0.1 works properly. ---
**Author:** ![Mojster](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/mojster/32/21209_2.png) [@Mojster](https://discuss.elastic.co/u/Mojster)\ **Post date:** [January 1, 2018, 6:38pm UTC](https://discuss.elastic.co/t/kibana-6-1-1-fatal-error-at-start/112986/7 "2018-01-01T18:38:35Z")
@Gourav_Kumar & @Winfield_Henry: Both of you are getting an similar error than this one, but it's not the same. Your's got solved in the thread I mentioned above. ---
**Author:** ![Winfield\_Henry](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/winfield_henry/32/69344_2.png) [@Winfield\_Henry](https://discuss.elastic.co/u/Winfield_Henry)\ **Post date:** [January 1, 2018, 7:37pm UTC](https://discuss.elastic.co/t/kibana-6-1-1-fatal-error-at-start/112986/8 "2018-01-01T19:37:30Z")
@Mojster Your solution in the other thread seems aimed at the kibana windows service start and the paths chosen for that. I am starting from an admin console using the kibana.bat file. Kibana starts and is running on 5601, but throws the reactcss.handleHover uncaught exception when accessing via browser. Also, deleting the optimize directory has no effect. It regenerates and the error is still there. ---
**Author:** ![tsullivan](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/tsullivan/32/31077_2.png) [@tsullivan](https://discuss.elastic.co/u/tsullivan)\ **Post date:** [January 2, 2018, 6:15pm UTC](https://discuss.elastic.co/t/kibana-6-1-1-fatal-error-at-start/112986/9 "2018-01-02T18:15:24Z")
I replied to the other topic ([Kibana 6.1.0. starts with error](https://discuss.elastic.co/t/kibana-6-1-0-starts-with-error/111754/26)) and offered some ideas about why these problems could be happening. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [January 30, 2018, 6:15pm UTC](https://discuss.elastic.co/t/kibana-6-1-1-fatal-error-at-start/112986/10 "2018-01-30T18:15:27Z")
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