This means PHP on the WHMCS server has been compiled with --with-curlwrappers which is
buggy and known to cause various
problems that have nothing to do with Centova Cast.
The best solution is to not use --with-curlwrappers when building PHP (as it will break not just Centova Cast, but any PHP script that uses the same stream handling features that Centova Cast uses), but we've implemented a workaround for the next build of Centova Cast to accomodate those who don't have control over their PHP build options.