iOS Subtext App Error "Unable to connect to activation service"

When downloading purchased books on the iPad application Subtext, the user receives an "Unable to connect to activation service" error message on the iOS Subtext App for iPad.

This issue occurs because the application sends requests with a 100-continue header, and doesn't honor the proxy's request to resend without it.

Procedure

1. Disable the Block advanced proxy bypass attempts advanced option, see our help topic, Configuring the web proxy.
2. Remember to click Save and restart.