diff --git a/adc2019system.py b/adc2019system.py
index 010353898189b830961bd2b2f9129cc6059aeddf..6f2e3e078b8bf01fdb7e86a6ff23b8665ccaab69 100644
--- a/adc2019system.py
+++ b/adc2019system.py
@@ -26,6 +26,9 @@ def load_config(path):
 def set_role(role_name, config_data):
     global role
 
+    if role is not None:
+        del role
+
     if role_name == 'host':
         role = Host(config_data)
     elif role_name == 'solver':
@@ -34,14 +37,17 @@ def set_role(role_name, config_data):
 def call_api(method, cmd, params):
 
     print(f'I: API Received: {cmd}')
-    if role is not None:
-        return role.call_api(method, cmd, params)
-    else:
-        if cmd == 'role':
-            if method == 'POST':
-                set_role(params['role'], params)
-                return {'role': role.type}
-            else:
+    if cmd == 'role':
+        if method == 'POST':
+            set_role(params['role'], params)
+            return {'role': role.type}
+        else:
+            if role is None:
                 return {'role': 'Undefined'}
+            else:
+                return {'role': self.type}
+    else:
+        if role is not None:
+            return role.call_api(method, cmd, params)
         else:
             return None
diff --git a/roles/solver.py b/roles/solver.py
index 113828a75e206cd40ddfc0a3e293c84da3a6297d..890c67cc549b4856402232fd387e6b949b82f430 100644
--- a/roles/solver.py
+++ b/roles/solver.py
@@ -16,6 +16,9 @@ class Solver(object):
         self.name = config['name']
         self.solver = importlib.import_module(f"solvers.{config['solver']}")
         self.thread = None
+    
+    def __del__(self):
+        self.stop_solver()
 
     def __repr__(self):
         return "Solver"