Multipart form bytes fail to decode on Python 3.15
Upgrading to Python 3.15 makes decoding multipart form uploads as UTF-8 fail with byte errors that worked before
Tier II · Emerging Problems that are still building up.
3 public reports · first reported 8 October 2026 · last reported 8 October 2026
What's going wrong
A developer parsing multipart form-data uploads reports that code which worked on Python 3.14 now raises a UTF-8 decode error on 3.15 release candidates.
AI-assisted: written with the help of AI from the reports. The idea report has the full summary.
In the idea report
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