# Why appear "connection lost" in browsers

**URL:** <https://discourse.nodered.org/t/why-appear-connection-lost-in-browsers/26907>\
**Category:** Dashboard\
**Created:** [19 May 2020 10:05 UTC](https://discourse.nodered.org/t/why-appear-connection-lost-in-browsers/26907 "2020-05-19T10:05:22Z")\
**Posts on this page:** 10\
**Page:** 1

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**Author:** ![TomLi](https://avatars.discourse-cdn.com/v4/letter/t/9fc29f/32.png) [@TomLi](https://discourse.nodered.org/u/TomLi)\
**Post date:** [19 May 2020 10:05 UTC](https://discourse.nodered.org/t/why-appear-connection-lost-in-browsers/26907/1 "2020-05-19T10:05:22Z")

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When I access ui by [https://xxx/ui/](https://xxx/ui/), it shows Connection lost.

please help me . Thank you !

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**Author:** ![kuema](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/kuema/32/6542_2.png) [@kuema](https://discourse.nodered.org/u/kuema)\
**Post date:** [19 May 2020 10:13 UTC](https://discourse.nodered.org/t/why-appear-connection-lost-in-browsers/26907/2 "2020-05-19T10:13:06Z")

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It means the websocket communication was interrupted, which can have multiple causes.

Are there any error messages in the browser's debug console (open the developer tools)?

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**Author:** ![TomLi](https://avatars.discourse-cdn.com/v4/letter/t/9fc29f/32.png) [@TomLi](https://discourse.nodered.org/u/TomLi)\
**Post date:** [19 May 2020 10:16 UTC](https://discourse.nodered.org/t/why-appear-connection-lost-in-browsers/26907/3 "2020-05-19T10:16:09Z")

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yes,

 ![error](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/6/6/66728d88f81c01f938d09f9db1646e13353c6610.jpeg)

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**Author:** ![TomLi](https://avatars.discourse-cdn.com/v4/letter/t/9fc29f/32.png) [@TomLi](https://discourse.nodered.org/u/TomLi)\
**Post date:** [19 May 2020 10:17 UTC](https://discourse.nodered.org/t/why-appear-connection-lost-in-browsers/26907/4 "2020-05-19T10:17:04Z")

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Has it anything with setting.js?

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**Author:** ![kuema](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/kuema/32/6542_2.png) [@kuema](https://discourse.nodered.org/u/kuema)\
**Post date:** [19 May 2020 10:18 UTC](https://discourse.nodered.org/t/why-appear-connection-lost-in-browsers/26907/5 "2020-05-19T10:18:26Z")

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No, more likely a browser, network or firewall issue.

Which browser are you using? Have you tried others browsers?

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<div class="post-metadata">

**Author:** ![TomLi](https://avatars.discourse-cdn.com/v4/letter/t/9fc29f/32.png) [@TomLi](https://discourse.nodered.org/u/TomLi)\
**Post date:** [19 May 2020 10:20 UTC](https://discourse.nodered.org/t/why-appear-connection-lost-in-browsers/26907/6 "2020-05-19T10:20:44Z")

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above picture used in Microsoft Edge,

in Chrome , will display this as follow:

 ![error](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/7/9/7904439400c5fa9f82a9198eda4c41bd4dccd408.jpeg)

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**Author:** ![afelix](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/afelix/32/9743_2.png) [@afelix](https://discourse.nodered.org/u/afelix)\
**Post date:** [19 May 2020 10:36 UTC](https://discourse.nodered.org/t/why-appear-connection-lost-in-browsers/26907/7 "2020-05-19T10:36:39Z")

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It appears the "connection lost" error is caused by the **Network Error 12030** from your earlier screenshot. It's an error I've seen referenced elsewhere before, in connection to websockets. It's thrown by the browser, specifically by a couple versions of Internet Explorer and Edge, and from what I remember (and a quick search now) nobody has really a clue what's causing it, and Microsoft is not responding to any questions either. It appears that after some inactivity on the websocket connection the browser closes it, but nobody really has details or more information. It doesn't just happen with Node-RED, but also common among people working with MFC/.NET kind of applications that use websockets.

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**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [19 May 2020 18:16 UTC](https://discourse.nodered.org/t/why-appear-connection-lost-in-browsers/26907/8 "2020-05-19T18:16:54Z")

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Hi @TomLi the error you get - i get (when viewing your dashboard) too.

I dont know what is causing it but strongly suggest you [secure](https://nodered.org/docs/user-guide/runtime/securing-node-red) your installation ASAP...

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/3X/d/4/d45d937af85da8a58fdd995920514aeb18913081.png)

... before it becomes a [cryptomining bot](https://discourse.nodered.org/t/about-unsecured-instances-of-node-red-having-a-crypto-mining-flow-automatically-deployed/6913)

You have no security on your broker or node-red (and who knows what else?)

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<div class="post-metadata">

**Author:** ![TomLi](https://avatars.discourse-cdn.com/v4/letter/t/9fc29f/32.png) [@TomLi](https://discourse.nodered.org/u/TomLi)\
**Post date:** [20 May 2020 00:49 UTC](https://discourse.nodered.org/t/why-appear-connection-lost-in-browsers/26907/9 "2020-05-20T00:49:32Z")

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thanks very much

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [19 June 2020 00:49 UTC](https://discourse.nodered.org/t/why-appear-connection-lost-in-browsers/26907/10 "2020-06-19T00:49:37Z")

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