KUBB_INVALID_SERVER_VARIABLE: Invalid server variable

Code: KUBB_INVALID_SERVER_VARIABLE Level: error

A server variable resolves to a value that its enum does not allow.

What happened

OpenAPI server URLs can contain {variable} placeholders. When a variable declares an enum, the value Kubb resolves it to must be in that list. This diagnostic fires when the resolved value is not.

How to fix it

• Pass a value that the enum allows, or make the default a member of the enum.
• Add the value to the enum if the server supports it.
• Remove the enum if the variable is open-ended.

Common causes

• An override passed to Kubb uses a value outside the variable's enum.
• The variable's default is not itself a member of its enum.
• The enum list is missing a value that the server actually supports.

Example

petStore.yaml

servers:
  - url: https://{env}.api.example.com
    variables:
      env:
        default: dev
        enum: [dev, prod]   # 'staging' is not allowed

Example output

Terminal

[KUBB_INVALID_SERVER_VARIABLE]: Invalid server variable value 'staging' for 'env' when resolving https://{env}.api.example.com. Valid values are: dev, prod.
  at: #/servers
  fix: Use one of the allowed enum values, or drop the enum on the 'env' server variable.
  see: https://kubb.dev/docs/5.x/reference/diagnostics/kubb-invalid-server-variable

See also

• Base URL guide
• Diagnostics reference