Loki Compactor fails with BadRequest (400) error when connecting to corporate S3 storage

Grafana Loki
1

I’m trying to connect Loki to a corporate S3 storage, but I’m getting an error in the compactor logs:

init compactor: failed to init delete store: failed to get s3 object: BadRequest: Bad Request
	status code: 400, request id: , host id: 
error initialising module: compactor
github.com/grafana/dskit/modules.(*Manager).initModule
	/src/loki/vendor/github.com/grafana/dskit/modules/modules.go:138
github.com/grafana/dskit/modules.(*Manager).InitModuleServices
	/src/loki/vendor/github.com/grafana/dskit/modules/modules.go:108
github.com/grafana/loki/v3/pkg/loki.(*Loki).Run
	/src/loki/pkg/loki/loki.go:531
main.main
	/src/loki/cmd/loki/main.go:129
runtime.main
	/usr/local/go/src/runtime/proc.go:283
runtime.goexit
	/usr/local/go/src/runtime/asm_amd64.s:1700
level=error ts=2025-11-17T10:42:05.609857992Z caller=log.go:223 msg="error running loki" err="init compactor: failed to init delete store: failed to get s3 object: BadRequest: Bad Request\n\tstatus code: 400, request id: , host id: \nerror initialising module: compactor

S3 Configuration:

loki:
  storage:
    bucketNames:
      admin: loki-dev-admin
      chunks: loki-dev-chunks
      ruler: loki-dev-ruler
    type: s3
    s3:
      accessKeyId: some_accesskey
      secretAccessKey: some_secret
      endpoint: s3dh-dev.dmp.example.com:9000
      insecure: true
      s3ForcePathStyle: true
      region: null
      signatureVersion: null

I’ve verified that the MinIO bucket is accessible with these credentials.