DVC Fetch: Silently Ignores Failed Git Authentication

[wescef-fahmad]

Bug Report

Description

When running fetch or an imported target, DVC tries to fetch the target's repo via git. If git is supplied with incorrect PAT token, DVC does not report authentication failure, instead it appears to fetch and reports "Everything is up to date."

Reproduce

1. Do a dvc import from another repo
2. Run dvc fetch
3. When prompted to authenticate, enter bad PAT token
4. No error is raised!

Expected

DVC should report an auth failure

Environment information

Output of dvc doctor:

$ dvc doctor
DVC version: 3.65.0 (pip)
-------------------------
Platform: Python 3.12.12 on Linux-6.8.0-1044-azure-x86_64-with-glibc2.35
Subprojects:
        dvc_data = 3.17.0
        dvc_objects = 5.2.0
        dvc_render = 1.0.2
        dvc_task = 0.40.2
        scmrepo = 3.6.1
Supports:
        azure (adlfs = 2025.8.0, knack = 0.12.0, azure-identity = 1.25.1),
        http (aiohttp = 3.12.9, aiohttp-retry = 2.9.1),
        https (aiohttp = 3.12.9, aiohttp-retry = 2.9.1),
        ssh (sshfs = 2025.2.0)
Config:
        Global: /home/azureuser/.config/dvc
        System: /etc/xdg/dvc
Cache types: symlink
Cache directory: ext4 on /dev/sdb1
Caches: local
Remotes: azure
Workspace directory: ext4 on /dev/sda1
Repo: dvc, git
Repo.site_cache_dir: /var/tmp/dvc/repo/0d9f8cd50b2b0f4097fcfa7092e688b0

Additional Information (if any):

[wescef-fahmad]

Anonymized output with -vv:

2026-02-20 03:58:29,095 DEBUG: v3.65.0 (pip), CPython 3.12.12 on Linux-x86_64
2026-02-20 03:58:29,095 DEBUG: command: /…/venv/bin/dvc fetch -vv model_weights/imported/model_file.pt
2026-02-20 03:58:29,095 TRACE: Namespace(..., targets=['model_weights/imported/model_file.pt'], ...)
2026-02-20 03:58:29,376 DEBUG: Assuming 'model_weights/imported/model_file.pt' to be a stage inside 'dvc.yaml'
2026-02-20 03:58:29,477 TRACE: params.yaml does not exist, it won't be used in parametrization
2026-02-20 03:58:29,587 TRACE: params.yaml does not exist, it won't be used in parametrization
2026-02-20 03:58:29,587 TRACE: Context during resolution of stage prepare_stage: {}
2026-02-20 03:58:29,588 DEBUG: Lockfile 'dvc.lock' needs to be updated.
2026-02-20 03:58:29,588 TRACE: No lock entry found for 'dvc.yaml:prepare_stage'
2026-02-20 03:58:29,589 TRACE: Context during resolution of stage annotate_stage: {}
2026-02-20 03:58:29,591 TRACE: Context during resolution of stage evaluate_stage: {}
2026-02-20 03:58:29,591 TRACE: No lock entry found for 'dvc.yaml:evaluate_stage'
2026-02-20 03:58:29,592 TRACE: Context during resolution of stage review_stage: {}
2026-02-20 03:58:29,592 TRACE: No lock entry found for 'dvc.yaml:review_stage'
2026-02-20 03:58:29,593 TRACE: Context during resolution of stage annotate_video_stage_1: {}
2026-02-20 03:58:29,595 TRACE: Context during resolution of stage annotate_video_stage_3: {}
2026-02-20 03:58:29,596 TRACE: Context during resolution of stage prep_yolo_internal_1: {}
2026-02-20 03:58:29,598 TRACE: Context during resolution of stage train_yolo_internal_1: {}
2026-02-20 03:58:29,602 TRACE: Context during resolution of stage train_yolo_internal_1_ext_1: {}
2026-02-20 03:58:29,605 TRACE: Context during resolution of stage train_yolo_internal_1_ext_1_ext_2: {}
2026-02-20 03:58:29,609 TRACE: Context during resolution of stage generate_video_internal_1: {}
...
2026-02-20 03:58:29,669 TRACE:   191.09 ms in collecting stages from /…/project_root
2026-02-20 03:58:29,670 TRACE:   328.80 mks in collecting stages from /…/venv
2026-02-20 03:58:29,671 TRACE:    68.80 mks in collecting stages from /…/tests
2026-02-20 03:58:29,672 TRACE:   338.00 mks in collecting stages from /…/.yolo_models
...
2026-02-20 03:58:29,740 DEBUG: Checking if stage 'model_weights/imported/model_file.pt' is in 'dvc.yaml'
2026-02-20 03:58:29,847 TRACE: params.yaml does not exist
2026-02-20 03:58:30,054 DEBUG: Creating external repo https://…/repo/_git/model-repo@<commit-hash>
2026-02-20 03:58:30,055 DEBUG: erepo: git clone 'https://…/repo/_git/model-repo/' to a temporary dir
2026-02-20 03:58:40,739 DEBUG: skipping index collection for data with invalid fsid
Collecting |0.00 [00:10, ?entry/s]
2026-02-20 03:58:41,081 DEBUG: Preparing to transfer data from remote://storage/files/md5 to /mnt/cache/project/files/md5
2026-02-20 03:58:41,121 DEBUG: Collecting status from '/mnt/cache/project'
Fetching
Everything is up to date.
2026-02-20 03:58:41,125 DEBUG: Analytics is disabled.
2026-02-20 03:58:41,125 TRACE: Process exiting with 0

[wescef-fahmad]

Tested that a direct git clone of the same repo does report fatal: Authentication failed for ...