Why flutter_secure_storage Hangs on Safari Web (and How to Fix It)

How Safari ITP's iframe storage partitioning causes flutter_secure_storage to hang at crypto.subtle — and how we fixed it with an in-memory token strategy

The questions this problem led to. Click a box to jump there.

FirstThat storeOn SafariSoButCheckstart1 why2 why3 why4 why5 why6 whyWhy flutter_secure_storage Hangs on Safari Web (and How to Fix It)5min Where does it break?It stalls between storing and reading the token Why does it stall?The web impl uses crypto.subtle and IndexedDB Why Safari but not Chrome?ITP partitions iframe storage, so crypto.subtle hangs silently How do we fix it?Drop storage I/O and keep the token in memory What about token loss on refresh?Next.js re-injects it via PostMessage for bidirectional sync Did it actually get fixed?Verified on Safari, Chrome, and refresh

start

Why flutter_secure_storage Hangs on Safari Web (and How to Fix It)5min

First

1 why

Where does it break?It stalls between storing and reading the token

That store

2 why

Why does it stall?The web impl uses crypto.subtle and IndexedDB

On Safari

3 why

Why Safari but not Chrome?ITP partitions iframe storage, so crypto.subtle hangs silently

4 why

How do we fix it?Drop storage I/O and keep the token in memory

But

5 why

What about token loss on refresh?Next.js re-injects it via PostMessage for bidirectional sync

Check

6 why

Did it actually get fixed?Verified on Safari, Chrome, and refresh

leads torelates tonot written

Start with this post →