Receiving error "HTTP/1.1 426 Upgrade Required". Is there a way we can allow requests with HTTP/1.0 in APIGEE?

[#1]

you can set in proxy as below.

<AssignMessage continueOnError="false" enabled="true" name="set-1">
  <Set>
    <FormParams>
      <FormParam name="myparam">{request.header.myparam}</FormParam>
    </FormParams>
    <Headers>
        <Header name="user-agent">{request.header.user-agent}</Header>
    </Headers>
    <QueryParams>
      <QueryParam name="name">{request.header.name}</QueryParam>
      <QueryParam name="address">{request.header.address}</QueryParam>
    </QueryParams>
    <!-- <Verb>GET</Verb> -->
    <Payload contentType="text/plain">42</Payload>
    <Path/>
    <ReasonPhrase>Bad request</ReasonPhrase>
    <StatusCode>400</StatusCode>
    <Verb>POST</Verb>
    <Verb>{my_variable}</Verb>
    <Version>1.1</Version>
  </Set>
  <AssignTo createNew="false" transport="http" type="response"/>
</AssignMessage>

ref: https://cloud.google.com/apigee/docs/api-platform/reference/policies/assign-message-policy#example-1...