diff --git a/src/image/utils/schema/triggers.py b/src/image/utils/schema/triggers.py
index 408f698f8..9b9fb0b8a 100644
--- a/src/image/utils/schema/triggers.py
+++ b/src/image/utils/schema/triggers.py
@@ -1,7 +1,8 @@
 import pydantic
 
 from datetime import datetime
-from typing import Dict, List, Literal, Optional
+from typing import Dict, List, Literal, Optional, Any
+from typing_extensions import Annotated
 
 
 LATEST_SCHEMA_VERSION = 1
@@ -20,10 +21,18 @@ class ImageUploadReleaseSchema(pydantic.BaseModel):
     """Schema of the release option for uploads in the image.yaml trigger"""
 
     end_of_life: datetime = pydantic.Field(alias="end-of-life")
-    risks: List[Literal["edge", "beta", "candidate", "stable"]]
+    risks: List[Literal[*KNOWN_RISKS_ORDERED]]
 
     model_config = pydantic.ConfigDict(extra="forbid")
 
+    @pydantic.field_validator("risks", mode="after")
+    def _ensure_non_empty_risks(cls, value):
+        if not value:
+            raise ImageTriggerValidationError(
+                "At least one upload risk must be present."
+            )
+        return value
+
 
 class ImageUploadSchema(pydantic.BaseModel):
     """Schema of each upload within the image.yaml files."""
@@ -31,30 +40,27 @@ class ImageUploadSchema(pydantic.BaseModel):
     source: str
     commit: str
     directory: str
-    release: Optional[Dict[str, ImageUploadReleaseSchema]]
+    release: Optional[Dict[str, ImageUploadReleaseSchema]] = None
 
     model_config = pydantic.ConfigDict(extra="forbid")
 
 
-
 class ChannelsSchema(pydantic.BaseModel):
     """Schema of the 'release' tracks within the image.yaml file."""
 
     end_of_life: datetime = pydantic.Field(alias="end-of-life")
-    stable: Optional[str]
-    candidate: Optional[str]
-    beta: Optional[str]
-    edge: Optional[str]
+    stable: str = None
+    candidate: str = None
+    beta: str = None
+    edge: str = None
 
     model_config = pydantic.ConfigDict(extra="forbid")
 
-    # TODO: Do we need the pre keyword? Causes the validator to be
-    #  called prior to other validation.
-    @pydantic.field_validator("stable", "candidate", "beta", "edge", mode="before")
-    def _check_risks(cls, values: List) -> List:
+    @pydantic.model_validator(mode="after")
+    def _check_risks(self, values: List) -> List:
         """There must be at least one risk specified."""
         error = "At least one risk must be specified per track."
-        if not any(values):
+        if not any([self.stable, self.candidate, self.beta, self.edge]):
             raise ImageTriggerValidationError(error)
 
         return values
@@ -64,13 +70,18 @@ class ImageSchema(pydantic.BaseModel):
     """Validates the schema of the image.yaml files."""
 
     version: str
-    upload: Optional[List[ImageUploadSchema]]
-    release: Optional[Dict[str, ChannelsSchema]]
+    upload: Optional[List[ImageUploadSchema]] = None
+    release: Optional[Dict[str, ChannelsSchema]] = None
 
     model_config = pydantic.ConfigDict(extra="forbid")
 
+    @pydantic.field_validator("version", mode="before")
+    def _ensure_version_is_str(cls, value: Any):
+        """Ensure that version is always cast to str."""
+        return str(value)
+
     @pydantic.field_validator("upload")
-    def ensure_unique_triggers(
+    def _ensure_unique_triggers(
         cls, v: Optional[List[ImageUploadSchema]]
     ) -> Optional[List[ImageUploadSchema]]:
         """Ensure that the triggers are unique."""
diff --git a/tests/unit/test_image_trigger_file_validator.py b/tests/unit/test_image_trigger_file_validator.py
new file mode 100644
index 000000000..e1e6615d9
--- /dev/null
+++ b/tests/unit/test_image_trigger_file_validator.py
@@ -0,0 +1,84 @@
+from pathlib import Path
+import pytest
+
+import src.image.prepare_single_image_build_matrix as prep_matrix
+from src.image.utils.schema.triggers import ImageTriggerValidationError
+from glob import glob
+from pathlib import Path
+
+
+def test_existing_image_trigger_files():
+
+    for oci_path in glob("oci/*"):
+        prep_matrix.load_trigger_yaml(Path(oci_path))
+
+
+def test_image_trigger_validator_missing_channel_risks():
+
+    image_trigger = {
+        "version": 1,
+        "release": {
+            "latest": {
+                "end-of-life": "2030-05-01T00:00:00Z",
+            },
+        },
+        "upload": [],
+    }
+    with pytest.raises(ImageTriggerValidationError):
+        prep_matrix.validate_image_trigger(image_trigger)
+
+
+def test_image_trigger_validator_missing_release_risks():
+
+    image_trigger = {
+        "version": 1,
+        "release": {
+            "latest": {
+                "end-of-life": "2030-05-01T00:00:00Z",
+                "candidate": "1.0-22.04_candidate",
+            },
+        },
+        "upload": [
+            {
+                "source": "canonical/rocks-toolbox",
+                "commit": "17916dd5de270e61a6a3fd3f4661a6413a50fd6f",
+                "directory": "mock_rock/1.2",
+                "release": {
+                    "1.2-22.04": {
+                        "end-of-life": "2030-05-01T00:00:00Z",
+                        "risks": [],
+                    }
+                },
+            },
+        ],
+    }
+    with pytest.raises(ImageTriggerValidationError):
+        prep_matrix.validate_image_trigger(image_trigger)
+
+
+def test_image_trigger_validator_minimal_input():
+
+    image_trigger = {
+        "version": 1,
+        "release": {
+            "latest": {
+                "end-of-life": "2030-05-01T00:00:00Z",
+                "candidate": "1.0-22.04_candidate",
+            },
+        },
+        "upload": [
+            {
+                "source": "canonical/rocks-toolbox",
+                "commit": "17916dd5de270e61a6a3fd3f4661a6413a50fd6f",
+                "directory": "mock_rock/1.2",
+                "release": {
+                    "1.2-22.04": {
+                        "end-of-life": "2030-05-01T00:00:00Z",
+                        "risks": ["beta"],
+                    }
+                },
+            },
+        ],
+    }
+
+    prep_matrix.validate_image_trigger(image_trigger)
diff --git a/tests/unit/test_prepare_single_image_build_matrix.py b/tests/unit/test_prepare_single_image_build_matrix.py
index a4874205d..b3c62eb8c 100644
--- a/tests/unit/test_prepare_single_image_build_matrix.py
+++ b/tests/unit/test_prepare_single_image_build_matrix.py
@@ -2,6 +2,10 @@
 import pytest
 
 import src.image.prepare_single_image_build_matrix as prep_matrix
+from src.image.utils.schema.triggers import ImageTriggerValidationError
+import yaml
+from glob import glob
+from pathlib import Path
 
 
 def test_is_track_eol():