Issue: unserialize(): Error at offset 0 of 13 bytes

ErrorException: unserialize(): Error at offset 0 of 13 bytes - vault/core/controller/ui/tools/integrate/vw.php:257 
Generated By: Budgetadvisoryservice, Today at 4:50 AM

Stack Trace
#0 [internal function]: XenForo_Application::handlePhpError(8, 'unserialize(): ...', '/home/...', 257, Array)
#1 /vault/core/controller/ui/tools/integrate/vw.php(257): unserialize('{"preview":1}')
#2 /vault/core/controller/ui/tools/integrate/vw.php(173): vw_UI_Tools_Integrate_Controller->get_integration()
#3 /vault/core/controller/ui/tools/integrate/vw.php(41): vw_UI_Tools_Integrate_Controller->manage()
#4 /library/vw/XenForo/ControllerPublic/Wiki/Tools.php(50): vw_UI_Tools_Integrate_Controller->execute()
#5 /library/XenForo/FrontController.php(351): vw_XenForo_ControllerPublic_Wiki_Tools->actionIndex()
#6 /library/XenForo/FrontController.php(134): XenForo_FrontController->dispatch(Object(XenForo_RouteMatch))
#7 /index.php(13): XenForo_FrontController->run()
#8 {main}
Request State
array(3) {
  ["url"] => string(98) "https://site.com/wiki-tools/?do=integrate&action=edit&nodetypeid=1&nodeid=237"
  ["_GET"] => array(4) {
    ["do"] => string(9) "integrate"
    ["action"] => string(4) "edit"
    ["nodetypeid"] => string(1) "1"
    ["nodeid"] => string(3) "237"
  }
  ["_POST"] => array(0) {
  }
}