Failed to load resource: the server responded with a status of 500 (Service unavailable (with message))

I'm getting the error when attempting to use Form Builder with Webform when I click on the message the following appears.

Recoverable fatal error: Argument 1 passed to drupal_http_build_query() must be an array, string given, called in C:\...\includes\common.inc on line 2268 and defined in drupal_http_build_query() (line 486 of C:\...\includes\common.inc).

I've flushed the cache and looked for any database updates but nothing seems to be working. If I were to disable this and use Webform by itself this error does not appear.