React Native Redux Connect报错：Cannot read property toLowerCase of undefined

Hey there! No need to apologize for asking basic questions—we all start somewhere, and troubleshooting weird regressions is totally part of the development journey. 😊

It’s really odd that this error shifted from only affecting real devices to hitting your simulator too, especially since you haven’t changed how you’re using react-redux or connect. Let’s walk through some common fixes and checks to get to the bottom of this:

• Check for unexpected dependency updates: Silent updates to react-redux, redux, or react-native can sometimes introduce breaking changes. Run this command to see if any relevant packages were updated recently:

  npm list react-redux redux react-native
  

  (Use yarn list instead if you’re using Yarn.)

• Verify your Redux store setup: Even if your connect usage is the same, double-check that your root component is properly wrapped with <Provider store={store}>, and that your store is being created correctly (no typos in reducers, middleware, or initial state).

• Audit mapStateToProps/mapDispatchToProps: A tiny typo (like misspelling a state property or action creator) could be causing this, especially if a recent refactor slipped in an error you missed. Add some console.log statements here to confirm you’re accessing the right values.

• Clear all caches: React Native’s cache can hold onto old, broken code. Try these steps:

  • Reset the Metro bundler cache: npx react-native start --reset-cache
  • Uninstall and reinstall the app on both your simulator and real device

• Rule out conflicting packages: If you added any new libraries (like navigation tools, state management add-ons) recently, try removing them temporarily to see if the error disappears. Some packages can clash with Redux or React Native under the hood.

• Enable verbose logging: Since your stack trace wasn’t helpful, add logs in your PageLecture.js component to check if the store is accessible, if props from connect are coming through, and where exactly the error is triggering.

If you can share a small snippet of the relevant code from PageLecture.js (the connect call, mapStateToProps, etc.), that would make it even easier to pinpoint the issue.

内容的提问来源于stack exchange，提问作者Rachid Debu