How i ask a question about slim application Error

Question

i'm installing Eve-Ng in vmware to ubuntu. when i using the browserfor EVE-NG, I can't open the Router and iou,because i see slim application error+offset 255 + type errorexeption...like this:>>>> The application could not run because of the following error:

DETAILS Type: ErrorException Code: 8 Message: Undefined offset:255 File: /opt/unetlab/html/includes/api_nodes.php Line: 832 TRACE #0 /opt/unetlab/html/includes/api_nodes.php(832): Slim\Slim::handleErrors(8, 'Undefined offse...', '/opt/unetlab/ht...', 832, Array) #1 /opt/unetlab/html/api.php(669): apiStartLabNode(Object(Lab), '1', '0') #2 [internal function]: {closure}(Array) #3 /opt/unetlab/html/includes/Slim/Route.php(468): call_user_func_array(Object(Closure), Array) #4 /opt/unetlab/html/includes/Slim/Slim.php(1357): Slim\Route->dispatch() #5 /opt/unetlab/html/includes/Slim/Middleware/Flash.php(85): Slim\Slim->call() #6 /opt/unetlab/html/includes/Slim/Middleware/MethodOverride.php(92): Slim\Middleware\Flash->call() #7 /opt/unetlab/html/includes/Slim/Middleware/PrettyExceptions.php(67): Slim\Middleware\MethodOverride->call() #8 /opt/unetlab/html/includes/Slim/Slim.php(1302): Slim\Middleware\PrettyExceptions->call() #9 /opt/unetlab/html/api.php(1585): Slim\Slim->run() ...