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hrInvalidBackupSequence
Why this result matters
For hrInvalidBackupSequence, this code narrows the investigation to one engine boundary and should not be flattened into a generic exception. The decisive boundary is backup APIs were called in an order that violates the ESE external-backup state machine.
The stored Value is 0xC8000209 (negative JET error -521; -521). The HRESULT carries failure severity, so output state must be treated according to the individual API contract. Current ESE documentation uses JET_errInvalidBackupSequence for the corresponding published JET condition.
The first useful distinction is that for example, log enumeration advances the state so database files can no longer be opened in the earlier phase. Start by log the ordered API trace, open file handles, transition to log enumeration, and result of every close/end call. That separates a reproducible incident from a later generic cleanup or service error.
Do not confuse it with
This result specifically means that for example, log enumeration advances the state so database files can no longer be opened in the earlier phase. Related values below can appear in the same workflow but require a different response:
hrBackupNotAllowedYet | the instance is temporarily in a state where a backup cannot begin safely |
|---|---|
hrBackupInProgress | an external backup session is already active for the relevant ESE instance |
hrNoBackupDirectory | the external-backup operation has no destination directory configured for its temporary or copied artifacts |
Keep the original constant and hexadecimal value in telemetry. Replacing this result with “backup failed” or “database warning” removes the state information needed to select the next legal API call.
Forensic checklist
Preserve the first result before retries, cleanup, service restart, or file replacement changes the evidence. The diagnostic record should identify the exact API phase and the owner of every handle or artifact involved.
- Code-specific observation: log the ordered API trace, open file handles, transition to log enumeration, and result of every close/end call.
- Open backup file handles: record it together with this result and the timestamp of the first occurrence.
- Database/log enumeration transition: record it together with it and the timestamp of the first occurrence.
- Ordered API trace: record it together with it and the timestamp of the first occurrence.
- Instance and active backup owner: record it together with it and the timestamp of the first occurrence.
Use hashes, lengths, IDs, generation numbers, and redacted samples instead of copying directory contents or sensitive database values into routine logs. For this it investigation, a complete provenance chain is often more useful than a second automatic retry.
Objects and state involved
| Diagnostic layer | the ESE external-backup state machine and its single active session |
|---|---|
| Relevant API surface | JetBeginExternalBackup, JetGetAttachInfo, JetOpenFile/ReadFile/CloseFile, JetGetLogInfo, and JetEndExternalBackup |
| Code-specific boundary | backup APIs were called in an order that violates the ESE external-backup state machine |
| Narrow corrective direction | discard the context and repeat the documented begin, enumerate, open/read/close, logs, and end sequence |
Database files are enumerated and copied before the backup advances to the log-file phase., the engine tracks outstanding backup file handles and rejects calls made in the wrong phase.
Actions that can make diagnosis worse
- do not continue using a context after a sequence failure.
- do not omit the final end/abort path.
- do not discard the first lower-level Win32, RPC, or JET result merely because a later cleanup call returned a more familiar error.
Validation after correction
- Record it,
0xC8000209, the API name, the current phase, and all live context or file owners. - Verify the decisive condition by log the ordered API trace, open file handles, transition to log enumeration, and result of every close/end call.
- Apply only the narrow correction: discard the context and repeat the documented begin, enumerate, open/read/close, logs, and end sequence.
- After it, recreate any context invalidated by the failure; do not carry stale HBC, cursor, file, or restore-map state into the retry.
- repeat the smallest non-destructive test that reaches the same boundary, then verify both the return value and the resulting file, cursor, backup, or database state.
Acceptance criteria for a fix
A useful regression test for this HRESULT should force the condition “backup APIs were called in an order that violates the ESE external-backup state machine”, call one documented API transition, and assert the exact HRESULT. The corrected the case should change only the decisive precondition and should verify cleanup as well as the primary output. For the result backup or restore path, also prove that the resulting set can be enumerated and that no file handle or context remains active after finalization.
Technical references
- Begin external backup — API ordering, file semantics, warning/error interpretation, or recovery behavior relevant to it.
- Enumerating backup logs
- End external backup
- Microsoft JET_ERR enumeration
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