diff --git a/src/pylorax/api/errors.py b/src/pylorax/api/errors.py
index d6a90e8f..b714733c 100644
--- a/src/pylorax/api/errors.py
+++ b/src/pylorax/api/errors.py
@@ -24,6 +24,9 @@ BAD_COMPOSE_TYPE = "BadComposeType"
 # not convert into an integer.
 BAD_LIMIT_OR_OFFSET = "BadLimitOrOffset"
 
+# Returned from the API for all other errors from a /blueprints/* route.
+BLUEPRINTS_ERROR = "BlueprintsError"
+
 # Returned from the API for any other error resulting from /compose failing.
 BUILD_FAILED = "BuildFailed"
 
@@ -32,6 +35,13 @@ BUILD_FAILED = "BuildFailed"
 # a build that is not yet done.
 BUILD_IN_WRONG_STATE = "BuildInWrongState"
 
+# Returned from the API when some file is requested that is not present - a log
+# file, the compose results, etc.
+BUILD_MISSING_FILE = "BuildMissingFile"
+
+# Returned from the API for all other errors from a /compose/* route.
+COMPOSE_ERROR = "ComposeError"
+
 # Returned from the API when a blueprint name or other similar identifier is
 # given that contains invalid characters.
 INVALID_NAME = "InvalidName"
@@ -40,6 +50,12 @@ INVALID_NAME = "InvalidName"
 # what to compose.
 MISSING_POST = "MissingPost"
 
+# Returned from the API for all other errors from a /modules/* route.
+MODULES_ERROR = "ModulesError"
+
+# Returned from the API for all other errors from a /projects/* route.
+PROJECTS_ERROR = "ProjectsError"
+
 # Returned from the API when someone tries to modify an immutable system source.
 SYSTEM_SOURCE = "SystemSource"
 
diff --git a/src/pylorax/api/v0.py b/src/pylorax/api/v0.py
index c8e5e221..f96850c2 100644
--- a/src/pylorax/api/v0.py
+++ b/src/pylorax/api/v0.py
@@ -1139,7 +1139,7 @@ def v0_api(api):
                 with api.config["GITLOCK"].lock:
                     commits = take_limits(list_commits(api.config["GITLOCK"].repo, branch, filename), offset, limit)
             except Exception as e:
-                errors.append("%s: %s" % (blueprint_name, str(e)))
+                errors.append({"id": BLUEPRINTS_ERROR, "msg": "%s: %s" % (blueprint_name, str(e))})
                 log.error("(v0_blueprints_changes) %s", str(e))
             else:
                 blueprints.append({"name":blueprint_name, "changes":commits, "total":len(commits)})
@@ -1173,7 +1173,7 @@ def v0_api(api):
                 workspace_write(api.config["GITLOCK"].repo, branch, blueprint)
         except Exception as e:
             log.error("(v0_blueprints_new) %s", str(e))
-            return jsonify(status=False, errors=[str(e)]), 400
+            return jsonify(status=False, errors=[{"id": BLUEPRINTS_ERROR, "msg": str(e)}]), 400
         else:
             return jsonify(status=True)
 
@@ -1195,7 +1195,7 @@ def v0_api(api):
                 delete_recipe(api.config["GITLOCK"].repo, branch, blueprint_name)
         except Exception as e:
             log.error("(v0_blueprints_delete) %s", str(e))
-            return jsonify(status=False, errors=[str(e)]), 400
+            return jsonify(status=False, errors=[{"id": BLUEPRINTS_ERROR, "msg": str(e)}]), 400
         else:
             return jsonify(status=True)
 
@@ -1220,7 +1220,7 @@ def v0_api(api):
                 workspace_write(api.config["GITLOCK"].repo, branch, blueprint)
         except Exception as e:
             log.error("(v0_blueprints_workspace) %s", str(e))
-            return jsonify(status=False, errors=[str(e)]), 400
+            return jsonify(status=False, errors=[{"id": BLUEPRINTS_ERROR, "msg": str(e)}]), 400
         else:
             return jsonify(status=True)
 
@@ -1242,7 +1242,7 @@ def v0_api(api):
                 workspace_delete(api.config["GITLOCK"].repo, branch, blueprint_name)
         except Exception as e:
             log.error("(v0_blueprints_delete_workspace) %s", str(e))
-            return jsonify(status=False, errors=[str(e)]), 400
+            return jsonify(status=False, errors=[{"id": BLUEPRINTS_ERROR, "msg": str(e)}]), 400
         else:
             return jsonify(status=True)
 
@@ -1292,7 +1292,7 @@ def v0_api(api):
                 tag_recipe_commit(api.config["GITLOCK"].repo, branch, blueprint_name)
         except Exception as e:
             log.error("(v0_blueprints_tag) %s", str(e))
-            return jsonify(status=False, errors=[str(e)]), 400
+            return jsonify(status=False, errors=[{"id": BLUEPRINTS_ERROR, "msg": str(e)}]), 400
         else:
             return jsonify(status=True)
 
@@ -1381,7 +1381,7 @@ def v0_api(api):
                     with api.config["GITLOCK"].lock:
                         blueprint = read_recipe_commit(api.config["GITLOCK"].repo, branch, blueprint_name)
                 except Exception as e:
-                    errors.append("%s: %s" % (blueprint_name, str(e)))
+                    errors.append({"id": BLUEPRINTS_ERROR, "msg": "%s: %s" % (blueprint_name, str(e))})
                     log.error("(v0_blueprints_freeze) %s", str(e))
 
             # No blueprint found, skip it.
@@ -1399,7 +1399,7 @@ def v0_api(api):
                 with api.config["YUMLOCK"].lock:
                     deps = projects_depsolve(api.config["YUMLOCK"].yb, projects, blueprint.group_names)
             except ProjectsError as e:
-                errors.append("%s: %s" % (blueprint_name, str(e)))
+                errors.append({"id": BLUEPRINTS_ERROR, "msg": "%s: %s" % (blueprint_name, str(e))})
                 log.error("(v0_blueprints_freeze) %s", str(e))
 
             blueprints.append({"blueprint": blueprint.freeze(deps)})
@@ -1441,7 +1441,7 @@ def v0_api(api):
                     with api.config["GITLOCK"].lock:
                         blueprint = read_recipe_commit(api.config["GITLOCK"].repo, branch, blueprint_name)
                 except Exception as e:
-                    errors.append("%s: %s" % (blueprint_name, str(e)))
+                    errors.append({"id": BLUEPRINTS_ERROR, "msg": "%s: %s" % (blueprint_name, str(e))})
                     log.error("(v0_blueprints_depsolve) %s", str(e))
 
             # No blueprint found, skip it.
@@ -1458,7 +1458,7 @@ def v0_api(api):
                 with api.config["YUMLOCK"].lock:
                     deps = projects_depsolve(api.config["YUMLOCK"].yb, projects, blueprint.group_names)
             except ProjectsError as e:
-                errors.append("%s: %s" % (blueprint_name, str(e)))
+                errors.append({"id": BLUEPRINTS_ERROR, "msg": "%s: %s" % (blueprint_name, str(e))})
                 log.error("(v0_blueprints_depsolve) %s", str(e))
 
             # Get the NEVRA's of the modules and projects, add as "modules"
@@ -1487,7 +1487,7 @@ def v0_api(api):
                 available = projects_list(api.config["YUMLOCK"].yb)
         except ProjectsError as e:
             log.error("(v0_projects_list) %s", str(e))
-            return jsonify(status=False, errors=[str(e)]), 400
+            return jsonify(status=False, errors=[{"id": PROJECTS_ERROR, "msg": str(e)}]), 400
 
         projects = take_limits(available, offset, limit)
         return jsonify(projects=projects, offset=offset, limit=limit, total=len(available))
@@ -1506,7 +1506,7 @@ def v0_api(api):
                 projects = projects_info(api.config["YUMLOCK"].yb, project_names.split(","))
         except ProjectsError as e:
             log.error("(v0_projects_info) %s", str(e))
-            return jsonify(status=False, errors=[str(e)]), 400
+            return jsonify(status=False, errors=[{"id": PROJECTS_ERROR, "msg": str(e)}]), 400
 
         if not projects:
             msg = "one of the requested projects does not exist: %s" % project_names
@@ -1529,7 +1529,7 @@ def v0_api(api):
                 deps = projects_depsolve(api.config["YUMLOCK"].yb, [(n, "*") for n in project_names.split(",")], [])
         except ProjectsError as e:
             log.error("(v0_projects_depsolve) %s", str(e))
-            return jsonify(status=False, errors=[str(e)]), 400
+            return jsonify(status=False, errors=[{"id": PROJECTS_ERROR, "msg": str(e)}]), 400
 
         if not deps:
             msg = "one of the requested projects does not exist: %s" % project_names
@@ -1644,7 +1644,7 @@ def v0_api(api):
                     log.info("Updating repository metadata after adding %s failed", source["name"])
                     update_metadata(yb)
 
-            return jsonify(status=False, errors=[str(e)]), 400
+            return jsonify(status=False, errors=[{"id": PROJECTS_ERROR, "msg": str(e)}]), 400
 
         return jsonify(status=True)
 
@@ -1705,7 +1705,7 @@ def v0_api(api):
                 available = modules_list(api.config["YUMLOCK"].yb, module_names)
         except ProjectsError as e:
             log.error("(v0_modules_list) %s", str(e))
-            return jsonify(status=False, errors=[str(e)]), 400
+            return jsonify(status=False, errors=[{"id": MODULES_ERROR, "msg": str(e)}]), 400
 
         if module_names and not available:
             msg = "one of the requested modules does not exist: %s" % module_names
@@ -1728,7 +1728,7 @@ def v0_api(api):
                 modules = modules_info(api.config["YUMLOCK"].yb, module_names.split(","))
         except ProjectsError as e:
             log.error("(v0_modules_info) %s", str(e))
-            return jsonify(status=False, errors=[str(e)]), 400
+            return jsonify(status=False, errors=[{"id": MODULES_ERROR, "msg": str(e)}]), 400
 
         if not modules:
             msg = "one of the requested modules does not exist: %s" % module_names
@@ -1859,7 +1859,7 @@ def v0_api(api):
         try:
             uuid_cancel(api.config["COMPOSER_CFG"], uuid)
         except Exception as e:
-            return jsonify(status=False, errors=["%s: %s" % (uuid, str(e))]),400
+            return jsonify(status=False, errors=[{"id": COMPOSE_ERROR, "msg": "%s: %s" % (uuid, str(e))}]),400
         else:
             return jsonify(status=True, uuid=uuid)
 
@@ -1884,7 +1884,7 @@ def v0_api(api):
                 try:
                     uuid_delete(api.config["COMPOSER_CFG"], uuid)
                 except Exception as e:
-                    errors.append("%s: %s" % (uuid, str(e)))
+                    errors.append({"id": COMPOSE_ERROR, "msg": "%s: %s" % (uuid, str(e))})
                 else:
                     results.append({"uuid":uuid, "status":True})
         return jsonify(uuids=results, errors=errors)
@@ -1901,7 +1901,7 @@ def v0_api(api):
         try:
             info = uuid_info(api.config["COMPOSER_CFG"], uuid)
         except Exception as e:
-            return jsonify(status=False, errors=[str(e)]), 400
+            return jsonify(status=False, errors=[{"id": COMPOSE_ERROR, "msg": str(e)}]), 400
 
         if info is None:
             return jsonify(status=False, errors=[{"id": UNKNOWN_UUID, "msg": "%s is not a valid build uuid" % uuid}]), 400
@@ -1987,7 +1987,7 @@ def v0_api(api):
 
             # Make sure it really exists
             if not os.path.exists(image_path):
-                return jsonify(status=False, errors=["Build %s is missing image file %s" % (uuid, image_name)]), 400
+                return jsonify(status=False, errors=[{"id": BUILD_MISSING_FILE, "msg": "Build %s is missing image file %s" % (uuid, image_name)}]), 400
 
             # Make the image name unique
             image_name = uuid + "-" + image_name
@@ -2006,7 +2006,7 @@ def v0_api(api):
         try:
             size = int(request.args.get("size", "1024"))
         except ValueError as e:
-            return jsonify(status=False, errors=[str(e)]), 400
+            return jsonify(status=False, errors=[{"id": COMPOSE_ERROR, "msg": str(e)}]), 400
 
         status = uuid_status(api.config["COMPOSER_CFG"], uuid)
         if status is None:
@@ -2016,4 +2016,4 @@ def v0_api(api):
         try:
             return Response(uuid_log(api.config["COMPOSER_CFG"], uuid, size), direct_passthrough=True)
         except RuntimeError as e:
-            return jsonify(status=False, errors=[str(e)]), 400
+            return jsonify(status=False, errors=[{"id": COMPOSE_ERROR, "msg": str(e)}]), 400