Spent an hour debugging why my S3 bucket policy changes weren’t working. Turns out: browser cache.

The Problem

Changed S3 bucket policy to make a file public. Tested in Chrome. Still getting 403 Forbidden.

# Changed policy
aws s3api put-bucket-policy --bucket mybucket --policy ...

# Test in browser
https://mybucket.s3.amazonaws.com/file.pdf
# Still 403?? WHY?

Tried everything:

• Double-checked policy JSON
• Verified permissions
• Re-uploaded file
• Still 403!

The Cause

Browsers cache everything, including:

• Pages
• Downloads
• HTTP responses
• Error pages (yes, even 403s!)

Even though S3 policy changed, Chrome was showing me the cached 403 response.

The Solution

Use wget or curl instead of browsers for testing:

# Test with curl (no cache)
curl -I https://mybucket.s3.amazonaws.com/file.pdf

# Output:
HTTP/1.1 200 OK  # It works!

Policy was fine all along. Browser was lying to me.

Force Refresh in Browser

If you must use a browser:

Cmd+Shift+R (Mac)
Ctrl+Shift+R (Windows/Linux)

Hard refresh bypasses cache. But easier to just use curl.

Lesson

For testing HTTP changes:

• ✅ curl or wget - fresh request every time
• ❌ Browser - might show cached response

Browsers are great for end users. Terrible for testing infrastructure changes.

Now I know: S3 policy testing = curl, not Chrome.