The error message you are seeing (

400: Resumable ID from cookie could not be found in the datastore

) is related to the Ory Kratos continuity cookie, which is used to maintain the state of self-service flows (like login, registration, etc.) across browser redirects and interactions. This issue typically occurs when Ory Kratos cannot find the expected continuity container in its datastore, often because the required cookie (

ory_kratos_continuity

) is missing, inaccessible, or not set correctly. Here are some common causes and troubleshooting steps based on the knowledge sources: 1. Browser/Domain Mismatch: The self-service flow must be started and finished in the same browser. If you start the flow in one browser and try to finish it in another, or if you use tools like Postman or Insomnia, the cookie may not be available, leading to this error. Always use the same browser session for the entire flow. For testing, using cURL is recommended over browser-based API clients for consistency [[Kratos Debug Troubleshooting](https://www.ory.sh/docs/kratos/debug/troubleshooting)]. 2. Cookie Domain Issues: If Kratos is running under a subdomain and the UI is served from a different domain or subdomain, the continuity cookie may not be accessible to Kratos after a redirect (e.g., after OIDC authentication). Currently, the domain for the

ory_kratos_continuity

cookie is not configurable, which can cause issues in multi-domain or subdomain setups. This is a known limitation and has been discussed in the community [[Github Issue: ory_kratos_continuity cookie has no domain set](https://github.com/ory/kratos/issues/2713)]. 3. API Flows and Continuity: In API flows (as opposed to browser flows), the continuity container is stored in a cookie, which may not make sense or work as expected. This can lead to the error you are seeing if the API client does not handle cookies properly. There is ongoing discussion about improving this behavior [[Traits from the Update Registration API Flow payload with OIDC get lost](https://github.com/ory/network/issues/345)]. What you can do: - Ensure you are using the same browser session for the entire flow. - If you are using custom domains or subdomains, be aware of the cookie domain limitations. - For API flows, make sure your client handles cookies correctly, or consider using browser flows if possible. - If you are running into this due to domain issues, there is currently no official workaround to configure the continuity cookie domain, but this is recognized as a valid feature request by the Ory team. If you need more specific help, providing details about your deployment (domains, flow type, etc.) can help narrow down the root cause. For more information, see the official troubleshooting guide and related GitHub issues: - [Kratos Debug Troubleshooting](https://www.ory.sh/docs/kratos/debug/troubleshooting) - [Github Issue: ory_kratos_continuity cookie has no domain set](https://github.com/ory/kratos/issues/2713) - [Traits from the Update Registration API Flow payload with OIDC get lost](https://github.com/ory/network/issues/345)