Expo SDK 50 and expo-router 3 upgrade: node_modules/expo-router/entry.js: .plugins[0][0] must be a string, object, function

[imckain]

After upgrading expo and expo-router to latest I am getting this error : node_modules/expo-router/entry.js: .plugins[0][0] must be a string, object, function

I followed all the breaking change fixes in Evan's medium article (here) on expo-router v3 release.

I am not able to share much code, which is why I am opening a discussion rather than an issue; if you have any thoughts and would like a snippet of something specific I can possibly provide that, but has anyone come across this error yet? Not seeing anything in the GH issues.

Thanks

[brentvatne]

hey there! can you share your babel.config.js and metro.config.js?

[brentvatne]

@imckain - the error you're seeing is likely due to metro version mismatches. metro has a bunch of different packages and it's possible that either your lockfile is keeping an old version around or one of the dependencies is being brought in transitively. if you look in your lockfile, find any metro or metro-* package and ensure that it matches ^0.80.0 - most likely 0.80.4, but any 0.80.x should be fine

[Rubenvdveen]

@brentvatne Thank you, this was the issue for me aswel. However it was not a direct dependency, but a dependency of a dependency. Fixed it by upgrading that dependency!

[leimonio]

I had a similar issue these days and this is what I came up with.

After upgrading my project to expo@50, I've run into an issue where dev server is getting broken with the error:

Web Bundling failed 120ms (dist/index.js)
error: dist/index.js: .plugins[0] must be a string, object, function

Trying to debug the issue I found out that:

1. @expo/metro-config is using the metro-source-map plugin
2. metro-transform-worker tries to inject the functionMapBabelPlugin from metro-source-map to babel-transformer;
3. In my case this function was undefined leading to the above error.
4. The reason was that the metro-source-map@0.73.10 was used - which misses the above function

Resolution
After overriding to metro-source-map@0.80.5 the issue was resolved.

I've tried to find the metro-source-map version in the package and in the expo repository but it doesn't seem to be defined anywhere.

[leimonio]

@brentvatne Can I ask where are the metro-source-map and related metro package dependencies defined? I couldn't find any reference in the source code.

[Bonnev]

I can confirm that after running yarn install metro-source-map@0.80.5 the problem is resolved for me.

For reference: I had this error:

Android Bundling failed 399ms (D:\...\node_modules\expo-router\entry.js)
error: node_modules\expo-router\entry.js: .plugins[0] must be a string, object, function

Thank you @leimonio !

[gusgordon]

I'm also hitting this when upgrading

[brentvatne]

#26642 (reply in thread)

[bkleef]

For us this is also blocking development. We had to rollback to SDK 49 and router v2 because of this bug.

[movibe]

@EvanBacon you can help us? I have the same problem

[brentvatne]

#26642 (reply in thread)

[anistark]

I'm not using metro. Using nativewind

Getting error: index.ts: .plugins[0] must be a string, object, function

How to resolve it in that case? @brentvatne

[isnolan]

I have reproduced this problem through demo, and everyone is welcome to solve it together.

› Opening on iOS...
› Opening exp+obytesapp://expo-development-client/?url=http%3A%2F%2F192.168.2.8%3A8081 on iPhone 15 Pro Max
› Press ? │ show all commands
tailwindcss(ios) rebuilding... done
iOS Bundling failed 262ms (../../node_modules/expo-router/entry.js)
error: ../../node_modules/expo-router/entry.js: .plugins[0] must be a string, object, function

https://github.com/isnolan/expo-monorepo-example/tree/obytes

[lukzerom]

Have you run npx expo install --fix after SDK update? It helped me

[Jancera]

In my case I have a monorepo with one expo project installed. As I am using node_linker=hoisted the project have one shared node_modules, when I upgraded to expo 51 it caused a metro conflict with another project that is in this monorepo which is a ui package that was using react-native 0.72 which is older than the one used on expo 51. Because of that I had installed different metro-* packages versions which was causing this error. The solution was to upgrade my ui package's react-native, clear all caches, delete all node_modules and .lock file. After a fresh install I got everything working.

As @brentvatne stated, it is related to metro < 0.80.*