[React Scan] Failed to load. Must import React Scan before React runs.

[henryzhang03]

We use the script tag version. This appears "[React Scan] Failed to load. Must import React Scan before React runs." in our Next JS App Router project.

[danieldunderfelt]

Same here, running with npx react-scan@latest localhost:3000

It worked on the same site a few days ago 😩

Edit: For me it works with the script tag.

[RobPruzan]

@henryzhang03 is react-scan not working for you at all? Or is the log there, but it still works?

[henryzhang03]

@henryzhang03 is react-scan not working for you at all? Or is the log there, but it still works?

Works but log is there

[lxsmnsyc]

Usually this is the cache (either the dev build or the browser) lagging behind, have you tried deleting the cache and/or performing hard refresh?

[myudak]

yupp doesnt work

[myudak]

Same here, running with npx react-scan@latest localhost:3000

It worked on the same site a few days ago 😩

Edit: For me it works with the script tag.

how??

[lxsmnsyc]

@myudak oh you probably have to use react-scan's auto mode (which is basically loading react-scan from the CDN), without marking it async

[aztack]

Is Preact supported by react-scan? I've tried

• import scan and config manually
• add script tab before any other scripts
• npx react-scan localhost in my Preact 'hello world' project and keep getting this error.

update: I replace Preact to React and it works fine.

Will (and when) Preact be supported?

[mattbolanos]

i am receiving this error as well by using the script in Next.js App Router

[jkronlachner]

for me this was fixed using a plain <Script src="https://unpkg.com/react-scan/dist/auto.global.js" /> with the next/script in the head of my root layout.tsx. After that change make sure to clear the cache

[rodrigomoyano11]

This works for me! Thanks @jkronlachner!

[pivanov]

Also these can help too :) https://github.com/aidenybai/react-scan/tree/main/docs/installation