title: Creating Microsoft Flow Custom Connector fails with "Failed to upload file"
body: <p>I'm trying to create a Microsoft Flow Custom Connector, from an OpenAPI file, as described <a href="https://docs.microsoft.com/en-gb/connectors/custom-connectors/define-openapi-definition" rel="nofollow noreferrer">here</a>. </p>
  
  <p>It allows me to import the file, and correctly shows the actions in the UI. However when I come to click "Create Connector", it fails with the message "Failed to upload file XXX with size 7952 and sasUrl https://...".</p>
  
  <p>When I look in the browser network log, I see it is making OPTIONS requests to:
  <a href="https://pafeblobprodln.blob.core.windows.net/20180510t000000z97e13b316929479b8f4f2ae6ab7856ba/sage-200-flow-connectorswagger.json?sv=2017-04-17&amp;sr=c&amp;si=SASpolicy&amp;sig=XXX=&amp;comp=block&amp;blockid=XXX=" rel="nofollow noreferrer">https://pafeblobprodln.blob.core.windows.net/20180510t000000z97e13b316929479b8f4f2ae6ab7856ba/sage-200-flow-connectorswagger.json?sv=2017-04-17&amp;sr=c&amp;si=SASpolicy&amp;sig=XXX=&amp;comp=block&amp;blockid=XXX=</a></p>
  
  <p>Which are failing with "403 CORS not enabled or no matching rule found for this request". The request 'Origin' header is set to <a href="https://unitedkingdom.flow.microsoft.com" rel="nofollow noreferrer">https://unitedkingdom.flow.microsoft.com</a></p>
  
  <p>It looks like CORS isn't enabled on the blob container, at least for unitedkingdom.flow.microsoft.com.</p>
  
  <p>Using the same OpenAPI file, I can successfully create a <em>Logic Apps</em> Custom Connector, just not a <em>Flow</em> Custom Connector.</p>
  
  <p>Has anyone else encountered, and worked around this problem?</p>
  
  <p>Thanks</p>
  
  <p>Pete</p>