I am currently getting a 400 when trying to push a cache layer to Github Container Registry with docker buildx. This issue seems to be reproduced by others as well: https://github.com/docker/buildx/issues/271
docker buildx bake base --push
[+] Building 3.7s (10/10) FINISHED
=> [internal] load build definition from Dockerfile 0.1s
=> => transferring dockerfile: 238B 0.1s
=> [internal] load .dockerignore 0.1s
=> => transferring context: 2B 0.1s
=> resolve image config for docker.io/docker/dockerfile:1.1.7-experimental 0.4s
=> CACHED docker-image://docker.io/docker/dockerfile:1.1.7-experimental@sha256:de85b2f3a3e8a2f7fe48e8e84a65f6fdd5cd5183afa6412fff9caa6871649c44 0.0s
=> => resolve docker.io/docker/dockerfile:1.1.7-experimental@sha256:de85b2f3a3e8a2f7fe48e8e84a65f6fdd5cd5183afa6412fff9caa6871649c44 0.0s
=> [internal] load metadata for docker.io/library/python:3.8.4 0.3s
=> ERROR importing cache manifest from ghcr.io/data-apis/base:cache 0.3s
=> [stage-0 1/2] FROM docker.io/library/python:3.8.4@sha256:99307ba08435e9c7cddf3889ad2b2aec24c95272531c3db9ee6ff8939aea288c 0.0s
=> => resolve docker.io/library/python:3.8.4@sha256:99307ba08435e9c7cddf3889ad2b2aec24c95272531c3db9ee6ff8939aea288c 0.0s
=> CACHED [stage-0 2/2] RUN --mount=type=cache,target=/root/.cache/pip pip install record_api==1.2.1 0.0s
=> exporting to image 0.6s
=> => exporting layers 0.0s
=> => exporting manifest sha256:4e63f12df61ca8e98008438e80150b843a910ff8f4f8765d9934b763abb886ee 0.0s
=> => exporting config sha256:a79d89640ec268427404f9bca35ec3a52e70b9e0280429557724e32836d00cde 0.0s
=> => pushing layers 0.4s
=> => pushing manifest for ghcr.io/data-apis/base:1.2.1-0 0.2s
=> ERROR exporting cache 1.5s
=> => preparing build cache for export 0.0s
=> => writing layer sha256:11a88e76431345b48525c4e4d58d497810019f4bafdb5e2bd56dc34a05e09cc3 0.3s
=> => writing layer sha256:5573c4b3094956931fd68c310ae92c9eb1a787f0c77ac2730be9d16cce172d5e 0.1s
=> => writing layer sha256:6c9d897f37302ab8e2202260e76631265ca775bed68b5e6a0510bd09ddbe1fd5 0.1s
=> => writing layer sha256:989e6b19a265d6b8b7934e7ddd7dc07f6e2fc945b3a28dda9b8aecb12cdb30e0 0.1s
=> => writing layer sha256:a50d63766e9acf852b8363c7848473c09ab8bfb1c5964621dd20ba154c07d0ae 0.1s
=> => writing layer sha256:af14b6c2f8785723bceb5964c5dec1f0489b7750e9d4ec671e49bfba15d80a39 0.1s
=> => writing layer sha256:c4d25495f8226de0895993d1a78bb089efec11072bdb23c21cc3e53617e4e50a 0.1s
=> => writing layer sha256:d5f9aee4c996b95b09c62386a23494d5ad6a7e1deb0c2438b240f12a4c38ed8b 0.1s
=> => writing layer sha256:e9afc4f90ab09248d75c8081b6dfba749a7f7efdac704ced7e0ceb506e02fa4a 0.1s
=> => writing layer sha256:ee776f0e36afc19d8b1cf242d59ec0e5950aac4e8a60868a266dbc9515ba06f2 0.1s
=> => writing config sha256:628c554a06ff22b2b0a60640c50a8b440d64985f9aa9e06c1485b1190d12ee50 0.1s
=> => writing manifest sha256:4fae5ebb9b5ef5420de3b6067e8fb0c9bbdbb6fa978921c6cb639b88783392a8 0.5s
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> importing cache manifest from ghcr.io/data-apis/base:cache:
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> exporting cache:
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failed to solve: rpc error: code = Unknown desc = error writing manifest blob: failed commit on ref "sha256:4fae5ebb9b5ef5420de3b6067e8fb0c9bbdbb6fa978921c6cb639b88783392a8": unexpected status: 400 Bad Request