When a Jenkins job using this plugin has the "Server Side Encryption" flag enabled, it causes uploads to fail, emitting this error:

Caused by: hudson.remoting.ProxyException: software.amazon.awssdk.services.s3.model.S3Exception: Requests specifying Server Side Encryption with Customer provided keys must provide an appropriate secret key.

I believe the cause of this error is in Line 60 of src/main/java/hudson/plugins/s3/callable/S3BaseUploadCallable.java:

metadata.sseCustomerAlgorithm("AES256");

I think the fix might be to specify server-side encryption rather than a Customer-Managed KMS key as the code does now (which I believe is how this plugin worked up until the move to AWS SDK v2 after 498.v4c32ea_de55c2):

metadata.serverSideEncryption("AES256");