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W&B introduced a new API key format that is approximately 92 characters long (format: wandb_v1_<key_id>_<secret>). Older versions of the wandb SDK validate that keys are exactly 40 characters and reject the new format with this error: 
ValueError: API key must be 40 characters long, yours was 92
or, on some dedicated instances: 
ERROR API key must be 40 characters long, yours was 92
Fix: upgrade the wandb SDK The simplest fix is to upgrade to the latest wandb package, which accepts both the legacy 40-character format and the new 92-character format: 
pip install -U wandb
After upgrading, re-authenticate with your new key: 
wandb login --relogin
Note on the new key generation flow When you generate a new key from wandb.ai/authorize, W&B now displays the key only once at creation time. Copy it immediately — you cannot retrieve it again after closing the dialog. If you lose it, you will need to generate a new key. If you cannot upgrade the SDK If your environment requires a pinned SDK version that predates the new key format:
  • Check whether your account still has an older-format key active. If so, keep using it — legacy 40-character keys continue to work and are not automatically revoked when the new format is issued.
  • If you have already deleted your legacy key and cannot upgrade the SDK, contact W&B support. In some cases a legacy-format key can be issued for dedicated or on-premises instances.
  • As a temporary workaround, you can pass the key via the WANDB_API_KEY environment variable rather than using wandb login, which may bypass the local validation in older SDK versions:
export WANDB_API_KEY=<your-92-character-key>
python train.py
Related error: key reported as too short (20 characters) A separate error — API key must have 40+ characters, has 20 — can appear when calling wandb.Api().viewer.generate_api_key() programmatically in certain SDK versions. This is a different issue from the key format migration. Upgrade the SDK to resolve it; if the error persists after upgrading, contact support.
API Keys Authentication SDK