code: @RequirePOST
      public synchronized void doClearError(StaplerRequest req, StaplerResponse rsp) throws IOException, ServletException {
          getACL().checkPermission(getPermission());
  
          if(workerThread!=null && !workerThread.isRunning())
              workerThread = null;
          rsp.sendRedirect(".");
      }
docs: Clears the error status.