> ## Documentation Index > Fetch the complete documentation index at: https://docs.fjall.io/llms.txt > Use this file to discover all available pages before exploring further. # cfn.validation > AWS rejected a resource configuration CloudFormation refused a resource because AWS would not accept its configuration. The cause could not be attributed automatically. It may sit in the resource configuration, in a name already taken in your account, or in a regional restriction. ## Why this happens * A property value AWS refuses, such as an invalid combination of settings on a single resource. * A name collision. The resource's name is already taken by an existing resource in your account, often one created outside Fjall. * An unsupported value in the target region, such as an instance type or feature that region does not offer. ## How to fix it 1. Read the provider reason on the deployment's detail page. CloudFormation's verbatim status reason names the property and the value it rejected. 2. Correct the resource configuration in `infrastructure.ts`. Change the rejected property to a value AWS accepts in your target region. 3. If the reason describes a name collision, rename the resource in `infrastructure.ts`, or remove the conflicting resource if it is no longer needed. 4. Run `fjall deploy` again with the corrected configuration. ## What Fjall shows you The failure surfaces on the deployment's detail page on fjall.io, in the CLI's Error Detail block, and in the deployments list row title. The detail page carries the stable code, a per-occurrence detail sentence, the provider's verbatim reason, and the remediation steps, along with the root cause resource from the stack analysis. ## Related The full deploy workflow from build to live. Command reference for deploying an application. How Fjall protects your stacks during a deploy.