Corruption of pinned erasure-coded content post migration

[rampall]

Description
Pinned content on my Bee node v2.5.0 that was erasure coded became inaccessible after upgrading to v2.6.0.

• swarm-cli pinning list still shows the pinned files.
• However, I cannot download them via curl or swarm-cli.
• If I unpin a file, I am able to download it (likely fetched fresh from the network), but then I would lose any pinned data that is no longer available on the network (e.g., due to postage stamp expiry).

Steps - Not likely Reproducable

1. Pin erasure-coded content on Bee v2.5.0
2. Upgrade Bee node to v2.6.0
3. Run swarm-cli pinning list → files still appear pinned
4. Try downloading pinned file with curl or swarm-cli → fails
5. Unpin the file
6. Retry download → succeeds (fetched fresh), but previously pinned-only data is permanently lost

Expected behavior

• Pinned files (including erasure coded) should remain accessible after upgrade, regardless of postage stamp expiry or network availability.
• Data migration after any bee update should have some fallback mechanism to prevent data corruption (?)

Environment (please complete the following information):

• Bee Node: Upgraded from v2.5.0 → v2.6.0
• Pinning CLI: swarm-cli
• OS: Debian
• Running Bee as a service: Yes

Additional context

• A similar issue occurred about a year ago, a few months after erasure coding was introduced.
• This suggests it may not be version-specific.
• Possibility: the first run after updating Bee may have encountered an RPC endpoint failure, interrupting data migration (Bee as a service keeps retrying on failure).

[Cafe137]

ffe6d7fc805ede4581af1a01d9fcedf21332cfe3353d74a4961e53c360d06342

This hash can be downloaded by any node, but cannot be pinned.

This hash has been uploaded with erasure coding.

[nugaon]

Maybe the problem was the root chunk was missing from the network and it got replaced by a dispersed replica that the pinning service does not take into account <-> retrieval does not save recovered root chunk to cache, and the pin does not retrieve the dispersed chunk from the network