How to debug React Native Expo-app crashing on iOS, after updating Expo SDK to version 49. Running the app in an iOS simulator works fine

I have an app built with React Native and Expo.
I had it on Expo SDK-version 48 and just upgraded to version 49. Now when I run: eas build and eas submit and then update my app via TestFlight on my phone, then it crashes immediately.

How do I solve this error - or figure out why it happens?
And my FYI: My projects name is hercules.

Solution attempt 1: App Store Connect Crash report

I can then send a crash report.

If I find it in App Store Connect and click 'Open in Xcode':

I then get a stack trace like this:

I guess this is the downside of using React Native and Expo. When the final build is generated like this, then it's harder to make sense of the stack trace. I can't make sense of what it says in above-shown image.

Solution attempt 2: Build logs in Expo.dev

I also checked the "Build logs" from the Expo.dev "Build" menu. There are 9mb of logs. Here is the start and the end (there are no timestamps, so I don't know if it's sorted in ascending or descending order):

Command line invocation:
    /Applications/Xcode.app/Contents/Developer/usr/bin/xcodebuild -workspace ./hercules.xcworkspace -scheme hercules -configuration Release -destination generic/platform=iOS -archivePath "/Users/expo/Library/Developer/Xcode/Archives/2023-07-09/hercules 2023-07-09 15.19.05.xcarchive" archive
User defaults from command line:
    IDEArchivePathOverride = /Users/expo/Library/Developer/Xcode/Archives/2023-07-09/hercules 2023-07-09 15.19.05.xcarchive
    IDEPackageSupportUseBuiltinSCM = YES
Prepare packages
Computing target dependency graph and provisioning inputs
Create build description
Build description signature: 2d65783870e59f558d579d6dedae71da
Build description path: /Users/expo/Library/Developer/Xcode/DerivedData/hercules-aiqjbxmtddzpiscjqedlczrddaee/Build/Intermediates.noindex/ArchiveIntermediates/hercules/IntermediateBuildFilesPath/XCBuildData/2d65783870e59f558d579d6dedae71da.xcbuilddata
note: Building targets in dependency order
CreateBuildDirectory /Users/expo/Library/Developer/Xcode/DerivedData/hercules-aiqjbxmtddzpiscjqedlczrddaee/Build/Intermediates.noindex/ArchiveIntermediates/hercules/InstallationBuildProductsLocation
    cd /Users/expo/workingdir/build/ios
    builtin-create-build-directory /Users/expo/Library/Developer/Xcode/DerivedData/hercules-aiqjbxmtddzpiscjqedlczrddaee/Build/Intermediates.noindex/ArchiveIntermediates/hercules/InstallationBuildProductsLocation
CreateBuildDirectory /Users/expo/Library/Developer/Xcode/DerivedData/hercules-aiqjbxmtddzpiscjqedlczrddaee/Build/Intermediates.noindex/ArchiveIntermediates/hercules/IntermediateBuildFilesPath
...
...
...
Validate /Users/expo/Library/Developer/Xcode/DerivedData/hercules-aiqjbxmtddzpiscjqedlczrddaee/Build/Intermediates.noindex/ArchiveIntermediates/hercules/InstallationBuildProductsLocation/Applications/hercules.app (in target 'hercules' from project 'hercules')
    cd /Users/expo/workingdir/build/ios
    builtin-validationUtility /Users/expo/Library/Developer/Xcode/DerivedData/hercules-aiqjbxmtddzpiscjqedlczrddaee/Build/Intermediates.noindex/ArchiveIntermediates/hercules/InstallationBuildProductsLocation/Applications/hercules.app
Touch /Users/expo/Library/Developer/Xcode/DerivedData/hercules-aiqjbxmtddzpiscjqedlczrddaee/Build/Intermediates.noindex/ArchiveIntermediates/hercules/InstallationBuildProductsLocation/Applications/hercules.app (in target 'hercules' from project 'hercules')
    cd /Users/expo/workingdir/build/ios
    /usr/bin/touch -c /Users/expo/Library/Developer/Xcode/DerivedData/hercules-aiqjbxmtddzpiscjqedlczrddaee/Build/Intermediates.noindex/ArchiveIntermediates/hercules/InstallationBuildProductsLocation/Applications/hercules.app
warning: Run script build phase '[CP-User] Generate app.manifest for expo-updates' will be run during every build because it does not specify any outputs. To address this warning, either add output dependencies to the script phase, or configure it to run in every build by unchecking "Based on dependency analysis" in the script phase. (in target 'EXUpdates' from project 'Pods')
** ARCHIVE SUCCEEDED **

Solution attempt 3: Other minor notes and attempts

• On my phone, after I've updated the app version, I don't see anything: It crashed immediately.
• I tried force-quitting the app, reinstalling it, rebooting my phone. None of it changes the outcome (still an immediate crash).
• I can run the app in an iOS simulator on my Mac (no crash, but I do get an Axios Network Error I'm debugging now).
• I've tried to install Sentry to get better error reporting. But I couldn't get this to work (the build started to fail). So I remove this again.

Quickfix: Downgrade to Expo version 48.0.18

I downgraded the version in package.json (amongst cleaned up my file from new versions that was bumped).
Then I deleted package-lock.json and node_modules.
Ran npm install
Ran npx expo install --fix
Ran npx expo start -c
Ran eas build
Ran eas submit

That worked. No crash. ¯\_(ツ)_/¯

I fixed this in my build after burning a day: the problem wasn't actually caused by expo; it was caused by an outdated version of expo-jest, which was failing because it had a reference to an outdated version of expo-config. I initially ignored it in expo-doctor because it was just a dev dependency, so I thought it didn't matter.

You can verify if this is your issue by running npx expo-doctor and seeing if it mentions something about expo-config. For upgrading to expo 49, I just replaced my "jest-expo" line in package.json to "jest-expo": "^49.0.0".