diff --git a/internal/template/http_handlers.go b/internal/template/http_handlers.go
index d0c5c4e..9bdc3bf 100644
--- a/internal/template/http_handlers.go
+++ b/internal/template/http_handlers.go
@@ -56,36 +56,21 @@ func fetchTemplate(c echo.Context) error {
 	return c.JSON(http.StatusOK, template)
 }
 
-func createOrUpdateTemplate(c echo.Context) error {
-	mgr := templateManagerFrom(c)
-	exists, err := mgr.hasTemplate(c.Request().Context(), c.Param("templateName"))
-	if err != nil {
-		return err
-	}
-	if !exists {
-		return createTemplate(c)
-	}
-
-	var body postTemplateRequestBody
-	err = json.NewDecoder(c.Request().Body).Decode(&body)
-	if err != nil {
-		return err
-	}
-
-	if body.ImageTag != nil || body.BuildArgs != nil {
-		return buildTemplate(c, body)
-	}
-
-	return updateTemplate(c, body)
-}
-
 func createTemplate(c echo.Context) error {
-	mgr := templateManagerFrom(c)
 	name := c.Param("templateName")
+	mgr := templateManagerFrom(c)
+
+	exists, err := mgr.hasTemplate(c.Request().Context(), name)
+	if err != nil {
+		return err
+	}
+
+	if exists {
+		return echo.NewHTTPError(http.StatusConflict)
+	}
 
 	var body createTemplateRequestBody
-	err := json.NewDecoder(c.Request().Body).Decode(&body)
-	if err != nil {
+	if err = json.NewDecoder(c.Request().Body).Decode(&body); err != nil {
 		return err
 	}
 
@@ -101,6 +86,29 @@ func createTemplate(c echo.Context) error {
 	return c.JSON(http.StatusOK, createdTemplate)
 }
 
+func updateOrBuildTemplate(c echo.Context) error {
+	mgr := templateManagerFrom(c)
+	exists, err := mgr.hasTemplate(c.Request().Context(), c.Param("templateName"))
+	if err != nil {
+		return err
+	}
+	if !exists {
+		return echo.NewHTTPError(http.StatusNotFound)
+	}
+
+	var body postTemplateRequestBody
+	err = json.NewDecoder(c.Request().Body).Decode(&body)
+	if err != nil {
+		return err
+	}
+
+	if body.ImageTag != nil || body.BuildArgs != nil {
+		return buildTemplate(c, body)
+	}
+
+	return updateTemplate(c, body)
+}
+
 func updateTemplate(c echo.Context, body postTemplateRequestBody) error {
 	name := c.Param("templateName")
 	mgr := templateManagerFrom(c)
diff --git a/internal/template/routes.go b/internal/template/routes.go
index 636dc49..c135e10 100644
--- a/internal/template/routes.go
+++ b/internal/template/routes.go
@@ -9,7 +9,8 @@ func DefineRoutes(g *echo.Group, services service.Services) {
 	g.Use(newTemplateManagerMiddleware(services))
 	g.GET("/templates", fetchAllTemplates)
 	g.GET("/templates/:templateName", fetchTemplate, validateTemplateName)
-	g.POST("/templates/:templateName", createOrUpdateTemplate, validateTemplateName)
+	g.PUT("/templates/:templateName", createTemplate, validateTemplateName)
+	g.POST("/templates/:templateName", updateOrBuildTemplate, validateTemplateName)
 	g.DELETE("/templates/:templateName", deleteTemplate, validateTemplateName)
 	g.GET("/templates/:templateName/:filePath", fetchTemplateFile, validateTemplateName, validateTemplateFilePath)
 	g.POST("/templates/:templateName/:filePath", updateTemplateFile, validateTemplateName, validateTemplateFilePath)
diff --git a/internal/template/template_manager.go b/internal/template/template_manager.go
index b00252c..ebec825 100644
--- a/internal/template/template_manager.go
+++ b/internal/template/template_manager.go
@@ -41,6 +41,7 @@ type buildTemplateOptions struct {
 }
 
 var errTemplateNotFound = errors.New("template not found")
+var errTemplateExists = errors.New("template already exists")
 var errBaseTemplateNotFound = errors.New("base template not found")
 var errTemplateFileNotFound = errors.New("template file not found")
 
diff --git a/web/src/api.ts b/web/src/api.ts
index 12ea5b9..c8d9ecb 100644
--- a/web/src/api.ts
+++ b/web/src/api.ts
@@ -1,6 +1,6 @@
 import { promiseOrThrow } from "./lib/errors";
 
-interface ApiErrorResponse {
+interface ApiErrorDetails {
 	code: string;
 	error: string;
 }
@@ -8,12 +8,13 @@ interface ApiErrorResponse {
 const API_ERROR_BAD_TEMPLATE = "BAD_TEMPLATE";
 const API_ERROR_WORKSPACE_EXISTS = "WORKSPACE_EXISTS";
 
-enum ApiError {
-	NotFound = "NOT_FOUND",
-	BadRequest = "BAD_REQUEST",
-	Internal = "INTERNAL",
-	Network = "NETWORK",
-}
+type ApiError =
+	| { type: "NOT_FOUND" }
+	| { type: "NETWORK" }
+	| { type: "BAD_REQUEST" }
+	| { type: "CONFLICT" }
+	| { type: "INTERNAL" }
+	| { type: "BAD_REQUEST"; details: ApiErrorDetails };
 
 async function fetchApi(
 	url: URL | RequestInfo,
@@ -21,22 +22,27 @@ async function fetchApi(
 ): Promise<Response> {
 	const res = await promiseOrThrow(
 		fetch(`${import.meta.env.VITE_API_URL}/api${url}`, init),
-		() => ApiError.Network,
+		() => ({ type: "NETWORK" }),
 	);
 	if (res.status !== 200) {
 		switch (res.status) {
 			case 400:
-				throw await res.json();
+				throw {
+					type: "BAD_REQUEST",
+					details: await res.json(),
+				};
 			case 404:
-				throw ApiError.NotFound;
+				throw { type: "NOT_FOUND" };
+			case 409:
+				throw { type: "CONFLICT" };
 			default:
-				throw ApiError.Internal;
+				throw { type: "INTERNAL" };
 		}
 	}
 	return res;
 }
 
-function isApiErrorResponse(error: unknown): error is ApiErrorResponse {
+function isApiErrorResponse(error: unknown): error is ApiErrorDetails {
 	return (
 		error !== null &&
 		error !== undefined &&
@@ -49,8 +55,7 @@ function isApiErrorResponse(error: unknown): error is ApiErrorResponse {
 export {
 	API_ERROR_BAD_TEMPLATE,
 	API_ERROR_WORKSPACE_EXISTS,
-	ApiError,
 	fetchApi,
 	isApiErrorResponse,
 };
-export type { ApiErrorResponse };
+export type { ApiError, ApiErrorDetails };
diff --git a/web/src/templates/api.ts b/web/src/templates/api.ts
index 1ffed05..e18fb93 100644
--- a/web/src/templates/api.ts
+++ b/web/src/templates/api.ts
@@ -6,7 +6,8 @@ import type {
 	TemplateImage,
 	BaseTemplate,
 } from "./types";
-import { fetchApi } from "@/api";
+import { ApiError, fetchApi } from "@/api";
+import { promiseOrThrow } from "@/lib/errors";
 
 function useTemplates() {
 	return useSWR(
@@ -17,7 +18,7 @@ function useTemplates() {
 }
 
 function useTemplate(name: string) {
-	return useSWR(
+	return useSWR<Template, ApiError>(
 		["/templates", name],
 		async (): Promise<Template> =>
 			fetchApi(`/templates/${name}`).then((res) => res.json()),
@@ -45,7 +46,7 @@ function useDeleteTemplate() {
 
 function useCreateTemplate() {
 	const [isCreating, setIsCreating] = useState(false);
-	const [error, setError] = useState<unknown | null>(null);
+	const [error, setError] = useState<ApiError | null>(null);
 	const { mutate } = useSWRConfig();
 
 	const createTemplate = useCallback(
@@ -60,14 +61,17 @@ function useCreateTemplate() {
 		}): Promise<Template | null> => {
 			try {
 				const res = await fetchApi(`/templates/${name}`, {
-					method: "POST",
+					method: "PUT",
 					body: JSON.stringify({ description, baseTemplate }),
 					headers: {
 						"Content-Type": "application/json",
 					},
 				});
 
-				const template: Template = await res.json();
+				const template = await promiseOrThrow<Template, ApiError>(
+					res.json(),
+					() => ({ type: "INTERNAL" }),
+				);
 				mutate(["/templates", name], template, {
 					populateCache: (newTemplate) => newTemplate,
 					revalidate: false,
@@ -75,7 +79,7 @@ function useCreateTemplate() {
 
 				return template;
 			} catch (err: unknown) {
-				setError(err);
+				setError(err as ApiError);
 				return null;
 			} finally {
 				setIsCreating(false);
@@ -88,10 +92,12 @@ function useCreateTemplate() {
 }
 
 function useTemplateFile(templateName: string, filePath: string) {
-	return useSWR(filePath ? ["/templates", templateName, filePath] : null, () =>
-		fetchApi(`/templates/${templateName}/${filePath}`).then((res) =>
-			res.text(),
-		),
+	return useSWR<string, ApiError>(
+		filePath ? ["/templates", templateName, filePath] : null,
+		() =>
+			fetchApi(`/templates/${templateName}/${filePath}`).then((res) =>
+				res.text(),
+			),
 	);
 }
 
diff --git a/web/src/templates/new-template-dialog.tsx b/web/src/templates/new-template-dialog.tsx
index 0d04481..04c2e69 100644
--- a/web/src/templates/new-template-dialog.tsx
+++ b/web/src/templates/new-template-dialog.tsx
@@ -30,6 +30,8 @@ import {
 } from "@/components/ui/select";
 import { LoadingSpinner } from "@/components/ui/loading-spinner";
 import type { BaseTemplate } from "./types";
+import { useEffect } from "react";
+import { useToast } from "@/hooks/use-toast";
 
 const NewTemplateForm = object({
 	baseTemplate: nonempty(string()),
@@ -75,7 +77,8 @@ function TemplateFormContainer() {
 
 function TemplateForm({ baseTemplates }: { baseTemplates: BaseTemplate[] }) {
 	const router = useRouter();
-	const { createTemplate, isCreatingTemplate } = useCreateTemplate();
+	const { createTemplate, isCreatingTemplate, error } = useCreateTemplate();
+	const { toast } = useToast();
 	const form = useForm({
 		resolver: superstructResolver(NewTemplateForm),
 		disabled: isCreatingTemplate,
@@ -86,6 +89,36 @@ function TemplateForm({ baseTemplates }: { baseTemplates: BaseTemplate[] }) {
 		},
 	});
 
+	useEffect(() => {
+		if (!error) return;
+
+		switch (error.type) {
+			case "CONFLICT":
+				toast({
+					variant: "destructive",
+					title: "Template already exists",
+					description: "Please use another name for the template",
+				});
+				break;
+
+			case "NETWORK":
+				toast({
+					variant: "destructive",
+					title: "Failed to create the template",
+					description: "Network error",
+				});
+				break;
+
+			default:
+				toast({
+					variant: "destructive",
+					title: "Failed to create the template",
+					description: "Unknown error",
+				});
+				break;
+		}
+	}, [error, toast]);
+
 	async function onSubmit(values: Infer<typeof NewTemplateForm>) {
 		const createdTemplate = await createTemplate({
 			name: values.templateName,
diff --git a/web/src/templates/template-editor.tsx b/web/src/templates/template-editor.tsx
index 09d1c95..2f0fa1f 100644
--- a/web/src/templates/template-editor.tsx
+++ b/web/src/templates/template-editor.tsx
@@ -1,4 +1,4 @@
-import { API_ERROR_BAD_TEMPLATE, ApiError } from "@/api";
+import { API_ERROR_BAD_TEMPLATE } from "@/api";
 import { CodeMirrorEditor } from "@/components/codemirror-editor";
 import { Button } from "@/components/ui/button.tsx";
 import {
@@ -12,6 +12,8 @@ import {
 	SidebarMenuItem,
 	SidebarProvider,
 } from "@/components/ui/sidebar.tsx";
+import { Toaster } from "@/components/ui/toaster";
+import { useToast } from "@/hooks/use-toast";
 import { cn } from "@/lib/utils";
 import { Link, useRouter } from "@tanstack/react-router";
 import { ArrowLeft, ChevronDown, ChevronUp, Loader2 } from "lucide-react";
@@ -25,10 +27,8 @@ import {
 	createTemplateEditorStore,
 	useTemplateEditorStore,
 } from "./template-editor-store";
-import type { Template } from "./types";
-import { useToast } from "@/hooks/use-toast";
-import { Toaster } from "@/components/ui/toaster";
 import { TemplateEditorTopBar } from "./template-editor-top-bar";
+import type { Template } from "./types";
 
 function TemplateEditor() {
 	const { templateName, _splat } = templateEditorRoute.useParams();
@@ -43,13 +43,13 @@ function TemplateEditor() {
 	}
 
 	if (error || !template) {
-		if (error === ApiError.NotFound) {
+		if (error?.type === "NOT_FOUND") {
 			return <TemplateNotFound />;
 		}
 
 		let message = "";
-		switch (error) {
-			case ApiError.Network:
+		switch (error?.type) {
+			case "NETWORK":
 				message = "Having trouble contacting the server.";
 				break;
 			default:
@@ -178,11 +178,11 @@ function Editor() {
 
 	if (error || fileContent === undefined) {
 		let message = "";
-		switch (error) {
-			case ApiError.NotFound:
+		switch (error?.type) {
+			case "NOT_FOUND":
 				message = "This file does not exist in the template.";
 				break;
-			case ApiError.Network:
+			case "NETWORK":
 				message = "Having trouble contacting the server.";
 				break;
 			default: