diff --git a/plugins/CuraEngineBackend/CuraEngineBackend.py b/plugins/CuraEngineBackend/CuraEngineBackend.py
index 3dd0589865..6a8a4a7347 100755
--- a/plugins/CuraEngineBackend/CuraEngineBackend.py
+++ b/plugins/CuraEngineBackend/CuraEngineBackend.py
@@ -720,9 +720,12 @@ class CuraEngineBackend(QObject, Backend):
     ##  Creates a new socket connection.
     def _createSocket(self, protocol_file: str = None) -> None:
         if not protocol_file:
+            if not self.getPluginId():
+                Logger.error("Can't create socket before CuraEngineBackend plug-in is registered.")
+                return
             plugin_path = PluginRegistry.getInstance().getPluginPath(self.getPluginId())
             if not plugin_path:
-                Logger.log("e", "Could not get plugin path!", self.getPluginId())
+                Logger.error("Could not get plugin path!", self.getPluginId())
                 return
             protocol_file = os.path.abspath(os.path.join(plugin_path, "Cura.proto"))
         super()._createSocket(protocol_file)
diff --git a/plugins/UM3NetworkPrinting/src/Network/SendMaterialJob.py b/plugins/UM3NetworkPrinting/src/Network/SendMaterialJob.py
index 5abc3cfde4..49e088100d 100644
--- a/plugins/UM3NetworkPrinting/src/Network/SendMaterialJob.py
+++ b/plugins/UM3NetworkPrinting/src/Network/SendMaterialJob.py
@@ -92,9 +92,13 @@ class SendMaterialJob(Job):
         parts = []
 
         # Add the material file.
-        with open(file_path, "rb") as f:
-            parts.append(self.device.createFormPart("name=\"file\"; filename=\"{file_name}\""
-                                                    .format(file_name = file_name), f.read()))
+        try:
+            with open(file_path, "rb") as f:
+                parts.append(self.device.createFormPart("name=\"file\"; filename=\"{file_name}\""
+                                                        .format(file_name = file_name), f.read()))
+        except FileNotFoundError:
+            Logger.error("Unable to send material {material_id}, since it has been deleted in the meanwhile.".format(material_id = material_id))
+            return
 
         # Add the material signature file if needed.
         signature_file_path = "{}.sig".format(file_path)