# Saleor 3.15.21 — Release & Upgrade Intelligence
- **Product:** Saleor (https://saleor.io)
- **Version:** 3.15.21
- **Released:** Dec 19, 2023
- **Impact Score:** 5/10
- **Breaking Changes:** Not verified
- **Canonical Analysis:** https://changelogs.us/saleor/updates/3.15.21/

## Executive Summary (TL;DR)
Saleor 3.15.21. Source highlight: Handle invalid image MIME type during thumbnail generation - #15090

## Bug Fixes
- Fix collections order in `CheckoutLinesInfoByCheckoutTokenLoader` - #15079
- Fix `visible_to_user` makes unnecessary calls when the channel is not passed - #15059