Hello,
I have the same issue with Seafile Pro 7.1.5 and Wasabi - I also tried Scaleway S3-compatible storage object with the same error “SignatureDoesNotMatch”. I verified their implementation with s3cmd and have been able to connect, list and upload data to buckets.
I did some digging and as far as I have been able to find out you are not always sending x-amz-date signature element. Excerpt from the seafile.log file:
../common/s3-client.c(624): Authorization: AWS4-HMAC-SHA256 Credential=XXXREPLACEDXXX/20200719/nl-ams/s3/aws4_request,SignedHeaders=host;x-amz-content-sha256,Signature=08b0225fa37367e7197b6d47b80fc3febff9XXXREPLACEDbecb3ac25718b03a5d876
../common/s3-client.c(624): x-amz-content-sha256: ba34b37f9eef973dbeea0XXREPLACEDXX56e2a7c3ce230903e0650ff70
The document at Amazon says it is required: https://docs.aws.amazon.com/general/latest/gr/sigv4_elements.html
Also, the headers (or signature elements) must be sorted alphabetically (by lowercase) - this is how the Amazon calculates signature.
Attn: @daniel.pan