Why would onMount not ever fire after Vite upgrade?

[danawoodman]

in an existing sveltekit app (latest of everything: vite@7.1.2 svelte@5.38.1 @sveltejs/kit@2.29.1 @sveltejs/vite-plugin-svelte@6.1.2) i'm not able to get onMount (and before/afterNavigate and other lifecycle events to ever run. this has reliably happened every time i try to upgrade Vite past v5

i've set breakpoints in the actual afterNavigate function and I'm not seeing any callbacks register despite them clearly being setup in code (and working previously).

cannot reproduce this behavior in a new repo, so i guess i'm wondering how i could troubleshoot svelte not registering these callbacks after an upgrade? this is a very large established sveltekit app so its not trivial to setup a reproduction

other notes:

• using cloudflare workers with the cloudflare adapter
• have wiped my node_modules, .svelte-kit and other artifact folders
• have rebuilt my bun.lock file (using Bun)
• project is in a bun managed monorepo
• things worked just fine before vite upgrade

[danawoodman]

wow, after lots of troubleshooting i found this in our vite config and removing it fixed the issue!