BlobNotFound
Azure Blob service returns `BlobNotFound` (404) when the specified blob path does not exist in the addressed container.
Last reviewed: February 13, 2026|Editorial standard: source-backed technical guidance
What Does Blob Not Found Mean?
Blob reads, metadata checks, and downstream workflows fail immediately because the object key cannot be resolved at the requested path.
Common Causes
- -Blob name/path in the request URI is incorrect, including virtual directory segment mismatches.
- -Request points to the wrong container or storage account endpoint for the intended blob.
- -Client requests a blob version or snapshot that does not exist anymore.
- -Object was deleted or replaced while consumers still reference stale blob names.
How to Fix Blob Not Found
- 1Verify full blob URI (account, container, blob path) generated by the caller.
- 2List blobs in the target container to confirm exact blob key existence.
- 3If using versioning or snapshots, supply a valid version/snapshot identifier.
- 4Update stale references in manifests, queues, or metadata stores before retrying.
Step-by-Step Diagnosis for Blob Not Found
- 1Capture failing request URI, status code, and
x-ms-request-idfor correlation. - 2Confirm container exists first, then validate blob existence under that container.
- 3Inspect application logs for transformed or URL-encoded blob names that differ from stored key.
- 4Audit recent lifecycle actions (delete, move, rename, overwrite) affecting the blob path.
Blob Address and Key Integrity
- -Trace blob key generation in app code (example: date partition formatter writes
2026/02/13while reader expects2026-02-13). - -Verify URL encoding and casing behavior in client libraries (example: space normalization changes blob key from
report final.csvtoreport%20final.csv).
Versioning, Snapshot, and Lifecycle Validation
- -Inspect version/snapshot parameters on read requests (example: client requests stale version ID after retention policy cleanup).
- -Correlate not-found events with lifecycle rules (example: archive or delete policy removed blob earlier than consumer SLA).
How to Verify the Fix
- -Replay the same operation and confirm
BlobNotFoundno longer appears. - -Validate consuming services can read the blob path consistently across environments.
- -Monitor storage logs for sustained reduction in blob 404 failure patterns.
How to Prevent Recurrence
- -Centralize blob key construction logic to avoid producer/consumer naming drift.
- -Persist canonical blob URIs (and version IDs where needed) instead of rebuilding ad hoc paths.
- -Add integrity checks that verify referenced blobs exist before enqueueing downstream tasks.
Pro Tip
- -store a hash of the canonical blob URI alongside metadata so drift in path generation is detectable before runtime read failures.
Decision Support
Compare Guide
403 Forbidden vs 404 Not Found: When to Hide Resources
Use 403 for explicit access denial, or 404 to conceal resource existence when security policy requires reducing endpoint and object enumeration risk.
Compare Guide
404 Not Found vs 410 Gone: Missing vs Permanent Removal
Learn when to return 404 (missing or temporary absence) versus 410 (intentional permanent removal), including redirect and cache implications.
Playbook
Resource State Playbook (404 / 410 / ResourceNotFound)
Use this playbook to separate temporary missing-resource lookups from permanent removals, then fix scope, lifecycle, and identifier drift safely.
Official References
Provider Context
This guidance is specific to Azure services. Always validate implementation details against official provider documentation before deploying to production.