Error codes

liteio returns S3-shaped XML errors. Every body has the same envelope, so your existing error handling parses them unchanged:

<?xml version="1.0" encoding="UTF-8"?>
<Error>
  <Code>NoSuchBucket</Code>
  <Message>The specified bucket does not exist.</Message>
  <Resource>/my-bucket</Resource>
  <RequestId>abc123def456</RequestId>
</Error>

The RequestId is worth logging on the client side; it lines up with the server log entry for the same request when you need to trace one down.

The catalog

Code	HTTP	What it means
AccessDenied	403	Bad signature, revoked credential, or an IAM policy that denies the action.
AuthorizationHeaderMalformed	400	The Authorization header is present but malformed.
BucketAlreadyExists	409	The name is taken by another account.
BucketAlreadyOwnedByYou	409	You already own a bucket by this name.
BucketNotEmpty	409	You tried to delete a bucket with objects in it.
EntityTooLarge	400	A single-part object went over the 5 GB ceiling.
EntityTooSmall	400	A multipart part other than the last is under 5 MB.
ExpiredToken	400	The STS session token has expired.
IncompleteBody	400	The body was shorter than the declared Content-Length.
InternalError	500	An unexpected server fault. The server log has the detail.
InvalidAccessKeyId	403	No such access key.
InvalidArgument	400	A header or query parameter value is invalid.
InvalidBucketName	400	The bucket name breaks the S3 naming rules.
InvalidObjectName	400	The object key is empty or otherwise invalid.
InvalidPart	400	A listed multipart part is missing or its ETag does not match.
InvalidPartOrder	400	Parts in CompleteMultipartUpload are not in ascending order.
InvalidRange	416	The Range falls outside the object.
InvalidSignature	403	The signature does not match.
MalformedXML	400	The request XML does not parse.
MethodNotAllowed	405	That method is not valid for this resource.
MissingContentLength	411	A streaming request came in without Content-Length.
NoSuchBucket	404	The bucket does not exist.
NoSuchKey	404	The object does not exist.
NoSuchUpload	404	The multipart upload ID is unknown or already aborted.
NoSuchVersion	404	The object version does not exist.
NotImplemented	501	The feature is not implemented. See the compatibility matrix.
PreconditionFailed	412	A conditional header (If-Match, If-Unmodified-Since) was not met.
RequestTimeTooSkewed	403	The request clock is more than 15 minutes off the server.
SignatureDoesNotMatch	403	The computed signature does not match the request.
SlowDown	503	A set is below read quorum, or the server is shedding load. Back off and retry.
TooManyBuckets	400	The account hit the bucket-count limit.
XAmzContentSHA256Mismatch	400	The body hash did not match x-amz-content-sha256.

Two you will actually hit

RequestTimeTooSkewed almost always means the client clock has drifted. Run NTP on the client before you suspect liteio.

SlowDown is backpressure, not a bug. The right response is exponential backoff, which every AWS SDK already does for you. A steady stream of it means a set is degraded; check liteio_cluster_sets_below_read_quorum in metrics.