Incorrect Generation of AWS S3 "af-south-1" Region URL

Issues
1

Issue Description

Using S3-Compatible blob storage, and selecting the region “af-south-1”, the S3 url generated is “s3-af-south-1.amazonaws.com”, but the correct url is “s3.af-south-1.amazonaws.com”.

This is not a blocking issue because you can just give the correct URL as a custom region.

Expected Behavior

Requests s3.af-south-1 by default for af-south-1

Actual Behavior

Requests s3-af-south-1 by default for af-south-1

Reproduction Steps

Use s3 compatible blob storage with “af-south-1” region.

Relevant Log Output

2026-08-26T11:35:47Z ERROR Resource error (resource.error) reason = S3 error (store.s3-error) { reason = "reqwest: error sending request for url (https://s3-af-south-1.amazonaws.com/XYZ/ABC): error sending request for url (https://s3-af-south-1.amazonaws.com/XYZ/ABC): client error (Connect): dns error: failed to lookup address information: Name or service not known", causedBy = "crates/store/src/dispatch/blob.rs:52" }, url = "https://github.com/stalwartlabs/webui/releases/latest/download/webui.zip", details = "Failed to unpack application for prefixes: admin, account"

Stalwart Version

v0.16.x

Installation Method

Docker

Database Backend

RocksDB

Blob Storage

S3-compatible

Search Engine

Internal

Directory Backend

Internal

I have reviewed the documentation and FAQ and confirm that my issue is NOT addressed there.

on

I have searched this support forum (open and closed topics) and confirm this is not a duplicate.

on

I understand that topics in this category are triaged by a bot first but a human reply will follow up. If I’d prefer a human-only reply, I’ll add the no-ai tag to my topic.

on

2

This does appear to be a bug in how the built‑in “af-south-1” region is mapped to its endpoint. Stalwart’s S3 backend relies on the rust-s3 library’s Region enum, and Region::AfSouth1 resolves internally to s3-af-south-1.amazonaws.com instead of the correct s3.af-south-1.amazonaws.com. Since this mapping comes from the underlying S3 client library rather than Stalwart-specific config, your workaround of using the “Custom” region with the correct endpoint (s3.af-south-1.amazonaws.com) is the right approach until that mapping is corrected upstream.

Relevant code: crates/store/src/backend/s3/mod.rs, where the config’s region enum is mapped to the s3 crate’s Region variants (e.g. structs::S3StoreRegion::AfSouth1 => Region::AfSouth1).

This is an automated reply from the Stalwart Help Bot. Other community members may follow up if this answer is incomplete or wrong.

3

This has been fixed in Stalwart v0.16.20 by overriding the hostname used by the rust-s3 crate.