diff --git a/gns3server/modules/dynamips/__init__.py b/gns3server/modules/dynamips/__init__.py
index 3e278c25..b2667f93 100644
--- a/gns3server/modules/dynamips/__init__.py
+++ b/gns3server/modules/dynamips/__init__.py
@@ -474,7 +474,7 @@ class Dynamips(IModule):
             raise DynamipsError("Could not create configs directory: {}".format(e))
 
         try:
-            with open(local_base_config, "r") as f:
+            with open(local_base_config, "r", errors="replace") as f:
                 config = f.read()
             with open(config_path, "w") as f:
                 config = "!\n" + config.replace("\r", "")
diff --git a/gns3server/modules/dynamips/hypervisor.py b/gns3server/modules/dynamips/hypervisor.py
index e1cc2e29..20e49741 100644
--- a/gns3server/modules/dynamips/hypervisor.py
+++ b/gns3server/modules/dynamips/hypervisor.py
@@ -251,7 +251,7 @@ class Hypervisor(DynamipsHypervisor):
         output = ""
         if self._stdout_file and os.access(self._stdout_file, os.R_OK):
             try:
-                with open(self._stdout_file) as file:
+                with open(self._stdout_file, errors="replace") as file:
                     output = file.read()
             except OSError as e:
                 log.warn("could not read {}: {}".format(self._stdout_file, e))
diff --git a/gns3server/modules/dynamips/nodes/router.py b/gns3server/modules/dynamips/nodes/router.py
index 7bfe7e52..bfdc9c28 100644
--- a/gns3server/modules/dynamips/nodes/router.py
+++ b/gns3server/modules/dynamips/nodes/router.py
@@ -223,7 +223,7 @@ class Router(object):
             startup_config_path = os.path.join(self.hypervisor.working_dir, "configs", "{}.cfg".format(self.name))
             if os.path.isfile(startup_config_path):
                 try:
-                    with open(startup_config_path, "r+") as f:
+                    with open(startup_config_path, "r+", errors="replace") as f:
                         old_config = f.read()
                         new_config = old_config.replace(self.name, new_name)
                         f.seek(0)
@@ -239,7 +239,7 @@ class Router(object):
             private_config_path = os.path.join(self.hypervisor.working_dir, "configs", "{}-private.cfg".format(self.name))
             if os.path.isfile(private_config_path):
                 try:
-                    with open(private_config_path, "r+") as f:
+                    with open(private_config_path, "r+", errors="replace") as f:
                         old_config = f.read()
                         new_config = old_config.replace(self.name, new_name)
                         f.seek(0)
diff --git a/gns3server/modules/iou/__init__.py b/gns3server/modules/iou/__init__.py
index 86a51d60..74a3a444 100644
--- a/gns3server/modules/iou/__init__.py
+++ b/gns3server/modules/iou/__init__.py
@@ -421,7 +421,7 @@ class IOU(IModule):
                 if os.path.isfile(request["startup_config"]) and request["startup_config"] != config_path:
                     # this is a local file set in the GUI
                     try:
-                        with open(request["startup_config"], "r") as f:
+                        with open(request["startup_config"], "r", errors="replace") as f:
                             config = f.read()
                         with open(config_path, "w") as f:
                             config = "!\n" + config.replace("\r", "")
diff --git a/gns3server/modules/iou/iou_device.py b/gns3server/modules/iou/iou_device.py
index 8233240a..42a5cd6c 100644
--- a/gns3server/modules/iou/iou_device.py
+++ b/gns3server/modules/iou/iou_device.py
@@ -188,7 +188,7 @@ class IOUDevice(object):
             config_path = os.path.join(self._working_dir, "startup-config")
             if os.path.isfile(config_path):
                 try:
-                    with open(config_path, "r+") as f:
+                    with open(config_path, "r+", errors="replace") as f:
                         old_config = f.read()
                         new_config = old_config.replace(self._name, new_name)
                         f.seek(0)
@@ -611,7 +611,7 @@ class IOUDevice(object):
         output = ""
         if self._iou_stdout_file:
             try:
-                with open(self._iou_stdout_file) as file:
+                with open(self._iou_stdout_file, errors="replace") as file:
                     output = file.read()
             except OSError as e:
                 log.warn("could not read {}: {}".format(self._iou_stdout_file, e))
@@ -626,7 +626,7 @@ class IOUDevice(object):
         output = ""
         if self._iouyap_stdout_file:
             try:
-                with open(self._iouyap_stdout_file) as file:
+                with open(self._iouyap_stdout_file, errors="replace") as file:
                     output = file.read()
             except OSError as e:
                 log.warn("could not read {}: {}".format(self._iouyap_stdout_file, e))
diff --git a/gns3server/modules/vpcs/__init__.py b/gns3server/modules/vpcs/__init__.py
index 9c566ea1..7140d592 100644
--- a/gns3server/modules/vpcs/__init__.py
+++ b/gns3server/modules/vpcs/__init__.py
@@ -336,7 +336,7 @@ class VPCS(IModule):
                 if os.path.isfile(request["script_file"]) and request["script_file"] != config_path:
                     # this is a local file set in the GUI
                     try:
-                        with open(request["script_file"], "r") as f:
+                        with open(request["script_file"], "r", errors="replace") as f:
                             config = f.read()
                         with open(config_path, "w") as f:
                             config = config.replace("\r", "")
diff --git a/gns3server/modules/vpcs/vpcs_device.py b/gns3server/modules/vpcs/vpcs_device.py
index eb639954..5cd09489 100644
--- a/gns3server/modules/vpcs/vpcs_device.py
+++ b/gns3server/modules/vpcs/vpcs_device.py
@@ -170,7 +170,7 @@ class VPCSDevice(object):
             config_path = os.path.join(self._working_dir, "startup.vpc")
             if os.path.isfile(config_path):
                 try:
-                    with open(config_path, "r+") as f:
+                    with open(config_path, "r+", errors="replace") as f:
                         old_config = f.read()
                         new_config = old_config.replace(self._name, new_name)
                         f.seek(0)
@@ -388,7 +388,7 @@ class VPCSDevice(object):
         output = ""
         if self._vpcs_stdout_file:
             try:
-                with open(self._vpcs_stdout_file) as file:
+                with open(self._vpcs_stdout_file, errors="replace") as file:
                     output = file.read()
             except OSError as e:
                 log.warn("could not read {}: {}".format(self._vpcs_stdout_file, e))