Fixing the Key cannot be used on the captcha-api.yandex.ru domain error
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Updated at December 17, 2025
Issue description
When testing or setting up SmartCaptcha locally, you get this error:
Error: Key cannot be used on the captcha-api.yandex.ru domain
Solution
Check the list of addresses and names you use when debugging SmartCaptcha. Typically, such an error means there are now local addresses in the host list.
Add localhost and 127.0.0.1 to the host list in the SmartCaptcha settings.