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I was working on a React Native project with a group and was asked to use the iPhone 13 simulator as a model while working. I only had access to the iPhone 12 simulator, and I saw that my XCode was a version behind, so I updated it. Now with the new XCode, I am getting an error when I start the React Native server and try and open the iOS simulator. the error is shown below:

error code in console

Running this command with the suggested build with -s Assertions=1 reveals the following:

result of build command with flag

My package.json is as following:

packagejson file

Any idea what is going on or how to proceed? Expo seems to be able to run, but trying to open the simulator crashes the server. The project I am on is near tight deadlines and I am totally held up by this. Either a way to troubleshoot this error or a way to roll back my XCode install and just live with a dated simulator would be greatly appreciated.

Callum Reid
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5 Answers5

29

Figured it our thanks to ShepSims from https://github.com/expo/expo-cli/issues/2413 . Before being able to open the iOS simulator from the terminal, I needed to open XCode and open the simulator there. This mounts the simulator bundle, allowing later access by pressing i after running expo start.

Callum Reid
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I was receiving the same error as above with XCode command line tools installed only, no XCode installed.

I tried re-installing XCode command line tools which didn't do anything.

For me this was solved with advice mentioned at https://github.com/expo/expo-cli/issues/3871:

  • open Simulator.app, as it automatically sets the default device.
Nick Whiu
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It is not anything. It was solved by opening simulator from XCOde on my mac

Udit
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The fastest way from my point of view is "spotlight" (Cmd+Space) search for "Simulator", hit enter before running "expo start" in your terminal.

RichardBrowning
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You can solve the problem by using this command

sudo expo start

Or

manually open simulator

start app: react-native run-ios

manually do: Hardware -> Device -> select iOS -> select Device (different than before !)

that will open a second simulator

start the app again: react-native run-ios (expo start then press i)

this opens the app in the selected simulator

Note:- please stay open the silumater then press the i in the expo and same for the react-native run-ios command

Sachin Saini
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