Greetings from Syncfusion,
We would like to inform you that swagger document generator needs Http method instead of Routes. So, we kindly suggest you to replace the Route method to Http method. Refer the suggestion below to resolve the issue,
[Route("FileOperations")] | [HttpPost("FileOperations")]
-- | --
[Route("Download")] | [HttpGet("Download")]
[Route("Upload")] | [HttpPost("Upload")]
[Route("GetImage")] | [HttpGet("GerImage")]
You can also refer the below link for the further references,
https://stackoverflow.com/questions/62959061/swagger-error-ambiguous-http-method-for-action-actions-require-explicit-httpmeth