Turbopack Error: inner_of_uppers_lost_follower is not able to remove follower TaskId 17 (ProjectContainer::entrypoints) from TaskId 16 (EntrypointsOperation::new) as they don't exist as upper or follower edges

[Nkateko-code]

Turbopack version: 40672141
Next.js version: 0.0.0

Error message:

Turbopack Error: inner_of_uppers_lost_follower is not able to remove follower TaskId 17 (ProjectContainer::entrypoints) from TaskId 16 (EntrypointsOperation::new) as they don't exist as upper or follower edges

[Mr-Nilarnab]

Yep — that’s another internal Turbopack runtime bug, not your code’s fault.
The message:

Turbopack Error: inner_of_uppers_lost_follower is not able to remove follower TaskId ...

basically means the Turbopack task graph got out of sync — the build dependency tracker is trying to clean up a task (or “follower”) that no longer exists.

This usually happens when:

• You start/stop next dev repeatedly very quickly

• The .next/ cache is corrupted

• Turbopack hits an internal race condition while watching files (common in canary or nightly builds)

---

✅ Quick Fix Steps

1. Stop your dev server

Press Ctrl + C in your terminal.

2. Clear Next.js and Turbopack caches

rm -rf .next

or on Windows:

rmdir /s /q .next

Then also remove lockfiles if needed:

npm ci

(or yarn install --force)

3. Restart cleanly

npm run dev

---

✅ If it persists

Try disabling Turbopack temporarily:

next dev --no-turbo

If your app runs fine afterward, that confirms it’s a Turbopack bug — not your code.

---

✅ Long-term Fix / Tracking

This specific internal error (inner_of_uppers_lost_follower) is a known bug in experimental Turbopack versions, tracked in the Next.js repo:
👉 vercel/next.js/issues

You’re using a canary build (v16.0.1-canary.5-10-g406721415), so it’s cutting-edge but unstable.
You can roll back to a stable release:

npm install [email protected]

and then rebuild.

---

⚙️ Summary

Cause	Fix
Turbopack task graph corruption	Delete .next and restart
Cache corruption	npm ci
Canary instability	Downgrade to stable [email protected]
Just want it working	Run next dev --no-turbo

---

Would you like me to give you a one-liner PowerShell command that clears all caches and restarts your app cleanly on Windows?

Yep — that’s another **internal Turbopack runtime bug**, not your code’s fault. The message:

Turbopack Error: inner_of_uppers_lost_follower is not able to remove follower TaskId ...

basically means the Turbopack task graph got out of sync — the build dependency tracker is trying to clean up a task (or “follower”) that no longer exists.

This usually happens when:

• You start/stop next dev repeatedly very quickly
• The .next/ cache is corrupted
• Turbopack hits an internal race condition while watching files (common in canary or nightly builds)

---

✅ Quick Fix Steps

1. Stop your dev server

Press Ctrl + C in your terminal.

2. Clear Next.js and Turbopack caches

rm -rf .next

or on Windows:

rmdir /s /q .next

Then also remove lockfiles if needed:

npm ci

(or yarn install --force)

3. Restart cleanly

npm run dev

---

✅ If it persists

Try disabling Turbopack temporarily:

next dev --no-turbo

If your app runs fine afterward, that confirms it’s a Turbopack bug — not your code.

---

✅ Long-term Fix / Tracking

This specific internal error (inner_of_uppers_lost_follower) is a known bug in experimental Turbopack versions, tracked in the Next.js repo:
👉 [vercel/next.js/issues](https://github.com/vercel/next.js/issues)

You’re using a canary build (v16.0.1-canary.5-10-g406721415), so it’s cutting-edge but unstable.
You can roll back to a stable release:

npm install [email protected]

and then rebuild.

---

⚙️ Summary

Cause	Fix
Turbopack task graph corruption	Delete .next and restart
Cache corruption	npm ci
Canary instability	Downgrade to stable [email protected]
Just want it working	Run next dev --no-turbo

---