Btrfs generation mismatch
Btrfs records a generation in each tree block and in the parent pointer that references it. A parent transid verify failure means the expected and found generations differ, often after lost, misdirected, or incompletely persisted writes.
Understand the symptom
The error reports a logical address plus wanted and found transaction IDs. A valid redundant metadata copy may allow scrub to correct the block; without one, the mismatch is permanent and salvage may require a read-only rescue mount or btrfs restore with results independently verified.
What you may see
The kernel log shows a logical block with wanted and found generations.
Btrfs protects the volume after detecting metadata inconsistency.
The damaged tree may affect a limited root, snapshot, or directory branch.
The lower layer may not have persisted related metadata writes in order.
Protect the source
Repair decisions with incomplete tree history can discard reachable metadata.
It can repair from another valid copy but cannot invent missing metadata.
New commits can overwrite evidence needed to compare older tree roots.
Do this now
Disable services, balance, defrag, scrub, snapshot deletion, and automatic mount retries.
Capture device, logical address, wanted and found generations, tree errors, kernel version, and timeline.
Keep all RAID-profile members, missing devices, replacements, and original order.
Protect failing drives before tree traversal or full-volume salvage.
NEPFOSYS process
NEPFOSYS identifies the affected logical block, tree, generation, and available metadata copies.
Candidate roots and rescue methods are evaluated on images without committing new transactions.
Recovered subvolumes and files are checked because salvage can bypass normal checksum guarantees.
A clear next step
Start a case with the exact symptoms, incident timeline, prior attempts, encryption details, and the files that matter most. NEPFOSYS will route the case to the appropriate DFW intake or nationwide mail-in path.
Start with a case reviewQuestions, answered
It is the transaction generation the parent pointer expects the referenced tree block to contain.
Only when a valid redundant copy exists and can be read; otherwise the missing metadata cannot be recreated automatically.
Not on the only copy. Preserve all devices and attempt read-only salvage before any write-based repair.
DFW local · Nationwide mail-in