# `Content-MD5` field/header seems to have no effect with a presigned POST url
MinIO does not validate the Content-MD5 header or field on presigned POST uploads, so a known-bad checksum will not fail the upload. The maintainers agreed this should be supported for completeness, but until then rely on TLS for transport integrity rather than Content-MD5.
## Context from the issue
gh:minio/minio#20319: Issue minio/minio#20319 (closed, 18 comments): When POSTing with a presigned URL to Minio, I am unable to cause the upload to fail via specifying a known bad `Content-MD5` field and header.
## Expected Behavior
When uploading a file to Minio with a presigned URL and specifying a known bad `Content-MD5`, the upload should fail.
## Current Behavior
The upload succeeds.
## Possible Solution
Possibly I'm doing something wrong - if so, if you could point it out that'd be great, as I'm a bit stumped.
Otherwise presumably Minio needs to check the MD5 of the file against the header / field.
## Steps to Reproduce (for bugs)
*...