diff --git a/invokeai/app/services/model_install/__init__.py b/invokeai/app/services/model_install/__init__.py
index 79cd748243..00a33c203e 100644
--- a/invokeai/app/services/model_install/__init__.py
+++ b/invokeai/app/services/model_install/__init__.py
@@ -7,7 +7,6 @@ from .model_install_base import (
     ModelInstallJob,
     ModelInstallServiceBase,
     ModelSource,
-    ModelSourceValidator,
     UnknownInstallJobException,
     URLModelSource,
 )
@@ -20,7 +19,6 @@ __all__ = [
     "ModelInstallJob",
     "UnknownInstallJobException",
     "ModelSource",
-    "ModelSourceValidator",
     "LocalModelSource",
     "HFModelSource",
     "URLModelSource",
diff --git a/invokeai/app/services/model_install/model_install_base.py b/invokeai/app/services/model_install/model_install_base.py
index 3a796bb5da..c2c11341df 100644
--- a/invokeai/app/services/model_install/model_install_base.py
+++ b/invokeai/app/services/model_install/model_install_base.py
@@ -123,8 +123,6 @@ class URLModelSource(StringLikeSource):
 #       https://github.com/tiangolo/fastapi/discussions/9287
 
 ModelSource = Annotated[Union[LocalModelSource, HFModelSource, URLModelSource], Body(discriminator="type")]
-ModelSourceValidator = TypeAdapter(ModelSource)
-
 
 class ModelInstallJob(BaseModel):
     """Object that tracks the current status of an install request."""
@@ -147,7 +145,7 @@ class ModelInstallJob(BaseModel):
     def set_error(self, e: Exception) -> None:
         """Record the error and traceback from an exception."""
         self.error_type = e.__class__.__name__
-        self.error = traceback.format_exc()
+        self.error = "".join(traceback.format_exception(e))
         self.status = InstallStatus.ERROR
 
 
@@ -173,6 +171,10 @@ class ModelInstallServiceBase(ABC):
         """Call at InvokeAI startup time."""
         self.sync_to_config()
 
+    @abstractmethod
+    def stop(self) -> None:
+        """Stop the model install service. After this the objection can be safely deleted."""
+
     @property
     @abstractmethod
     def app_config(self) -> InvokeAIAppConfig:
diff --git a/invokeai/app/services/model_install/model_install_default.py b/invokeai/app/services/model_install/model_install_default.py
index fa32c3a491..9022fc100c 100644
--- a/invokeai/app/services/model_install/model_install_default.py
+++ b/invokeai/app/services/model_install/model_install_default.py
@@ -73,10 +73,6 @@ class ModelInstallService(ModelInstallServiceBase):
         self._models_installed = set()
         self._start_installer_thread()
 
-    def __del__(self) -> None:
-        """At GC time, we stop the install thread and release its resources."""
-        self._install_queue.put(STOP_JOB)
-
     @property
     def app_config(self) -> InvokeAIAppConfig:  # noqa D102
         return self._app_config
@@ -89,6 +85,10 @@ class ModelInstallService(ModelInstallServiceBase):
     def event_bus(self) -> Optional[EventServiceBase]:  # noqa D102
         return self._event_bus
 
+    def stop(self) -> None:
+        """Stop the install thread; after this the object can be deleted and garbage collected."""
+        self._install_queue.put(STOP_JOB)
+
     def _start_installer_thread(self) -> None:
         threading.Thread(target=self._install_next_item, daemon=True).start()
 
@@ -114,6 +114,7 @@ class ModelInstallService(ModelInstallServiceBase):
                 self._signal_job_errored(job, excp)
             finally:
                 self._install_queue.task_done()
+        self._logger.info("Install thread exiting")
 
     def _signal_job_running(self, job: ModelInstallJob) -> None:
         job.status = InstallStatus.RUNNING
diff --git a/invokeai/backend/model_manager/probe.py b/invokeai/backend/model_manager/probe.py
index b5f9227af2..7cade3cada 100644
--- a/invokeai/backend/model_manager/probe.py
+++ b/invokeai/backend/model_manager/probe.py
@@ -425,7 +425,7 @@ class TextualInversionCheckpointProbe(CheckpointProbeBase):
         elif token_dim == 1280:
             return BaseModelType.StableDiffusionXL
         else:
-            raise InvalidModelConfigException("Could not determine base type")
+            raise InvalidModelConfigException(f"{self.model_path}: Could not determine base type")
 
 
 class ControlNetCheckpointProbe(CheckpointProbeBase):
@@ -443,7 +443,7 @@ class ControlNetCheckpointProbe(CheckpointProbeBase):
                 return BaseModelType.StableDiffusion1
             elif checkpoint[key_name].shape[-1] == 1024:
                 return BaseModelType.StableDiffusion2
-        raise InvalidModelConfigException("Unable to determine base type for {self.checkpoint_path}")
+        raise InvalidModelConfigException("{self.model_path}: Unable to determine base type")
 
 
 class IPAdapterCheckpointProbe(CheckpointProbeBase):