I know that stomach-drop feeling when you open your S3 bucket and see zero objects. You didn't delete anything, but everything's gone. Nine times out of ten, a lifecycle rule you applied earlier is the reason. Let's fix that right now.
Step 1: Check Your Lifecycle Rules Immediately
Go to the S3 console, click your bucket name, then click the Management tab. Scroll down to Lifecycle rules. Look at each rule carefully.
What you're looking for is an Expiration action that's set to delete objects after a certain number of days. If you set a rule to expire objects after 1 day, and then applied it to a bucket with existing objects, those objects get deleted within 24 hours. That's exactly what happened.
Here's what a dangerous rule looks like in the console:
Lifecycle rule name: cleanup-old-files
Prefix: (blank — applies to whole bucket)
Expiration: Delete current versions after 1 day(s)
A blank prefix means the rule hits every object in the bucket. If you intended to clean up only logs in a logs/ folder, but left the prefix blank, you just nuked everything.
Step 2: Disable or Delete the Rule Right Now
Don't wait. While you're reading this, the rule could delete more objects if new ones are uploaded. Click the radio button next to the rule, then click Delete. Or, if you think you might need it later, click Edit and uncheck Expiration to stop the deletion.
After you delete or disable the rule, go back to the bucket overview. You'll still see zero objects because the ones that got expired are gone. But the rule won't eat anything new.
Step 3: Check If Versioning Was Enabled
Here's the moment where versioning saves your skin. If you had Bucket Versioning turned on before the lifecycle rule ran, the objects aren't permanently gone. They're just marked as expired versions.
To check, go to the Properties tab, then Bucket Versioning. If it says Enabled, you're in luck.
Now go to the bucket's Objects tab and click the Show versions toggle. You'll see a list with an object name, a version ID, and a Delete marker or Expired status for each one.
To recover a specific version, click the checkbox next to it, then click Actions > Restore. For a delete marker, you can just delete the marker, and the original version becomes the current one again.
If you have thousands of objects, doing this one by one is painful. Instead, use the AWS CLI. Here's a command that lists all versions in the bucket, including expired ones:
aws s3api list-object-versions --bucket your-bucket-name --query 'Versions[?IsLatest==`false`]' --output table
That shows you what's recoverable. To restore a specific version, you copy it back over itself with the --version-id flag:
aws s3api copy-object --bucket your-bucket-name --key path/to/object --copy-source your-bucket-name/path/to/object?versionId=YOUR_VERSION_ID
This creates a new current version with the old content. It's not fast, but it works.
Step 4: Check S3 Glacier or Deep Archive
If your lifecycle rule said "Transition to Glacier" rather than "Expire," your files might not be deleted — they're just cold. Check the bucket's Storage class column in the object list. If you see Glacier or Deep Archive, you need to restore them first.
Click the object, go to Actions, choose Restore from Glacier, and pick how many days you want the temporary copy. After the restore completes (can take hours or even a day), you'll see a Restore status. Then you can download it or copy it back to Standard.
The real fix here is knowing that a transition isn't a deletion — but it feels like one because you can't access the file normally.
Why This Happened: The Lifecycle Rule Applied Retroactively
Here's the part everyone misses: lifecycle rules don't just affect new objects. They apply to existing objects based on their creation date. If you create a rule on Tuesday that expires objects after 1 day, any object that's already 2 days old gets deleted within hours — not after 24 hours from when you created the rule.
The rule counts from the object's LastModified date. So the older the objects are, the faster they vanish after you enable the rule. That's why a bucket full of files from last week can be emptied in one afternoon if you set "expire after 1 day" and forgot to limit the prefix.
Less Common Variations
1. You Used a Prefix But Missed the Leading Slash
If you typed logs instead of logs/, the rule matches any key that starts with "logs" — including logistics/report.pdf. That could delete more than you planned. The console doesn't warn you about this.
2. Expired Object Delete Markers
If you had versioning on and previously deleted some objects, those delete markers can accumulate. A lifecycle rule with Expired object delete marker enabled will purge those markers permanently. That's usually harmless, but if you later wanted to undelete by removing the marker, it won't be there anymore.
3. Lifecycle Rules on a Replication Bucket
If your bucket is a destination for S3 Replication, and you applied a lifecycle rule to the destination bucket thinking it would only affect duplicate data, you might have deleted the only copy. Replication doesn't protect against lifecycle rules on the destination. You need to carefully design rules for both source and destination buckets.
Prevention: What to Do So This Never Happens Again
First, enable versioning on every S3 bucket that holds anything you care about. The cost is tiny, and it gives you a safety net for accidental deletes, overwrites, and lifecycle mistakes. You can't enable versioning retroactively for objects that are already gone, but you can protect everything from this point on.
Second, when you create a lifecycle rule, always start with a prefix. If you want to test, create a rule that only applies to a folder like test/ and upload a dummy file to see what happens. Don't test on your production data.
Third, set expiration to at least 30 days for the first pass. You can always shorten it later after you watch how it behaves. There's no reason to ever expire objects after 1 day unless you're dealing with transient temp files.
Fourth, turn on S3 Inventory for the bucket. It gives you a daily CSV listing all objects and their storage classes. If something goes wrong, you know exactly what existed yesterday, which makes recovery or verification a lot easier.
Finally, keep a backup. S3 is not a backup. If you're storing your only copy of important files in S3 — even with versioning — you're still one bad day away from losing them. Use S3 Cross-Region Replication or copy critical data to another bucket in another account.
Lifecycle rules are like a pruning saw — they cut fast and don't ask questions. Now you know how to check the blade, and how to bandage the wound when it's already too late.