diff --git a/site/src/api/api.ts b/site/src/api/api.ts
index 013c018d5c656..6b38515a74f1a 100644
--- a/site/src/api/api.ts
+++ b/site/src/api/api.ts
@@ -24,6 +24,7 @@ import type dayjs from "dayjs";
 import userAgentParser from "ua-parser-js";
 import { OneWayWebSocket } from "../utils/OneWayWebSocket";
 import { delay } from "../utils/delay";
+import { type FieldError, isApiError } from "./errors";
 import type {
 	DynamicParametersRequest,
 	PostWorkspaceUsageRequest,
@@ -390,6 +391,15 @@ export class MissingBuildParameters extends Error {
 	}
 }
 
+export class ParameterValidationError extends Error {
+	constructor(
+		public readonly versionId: string,
+		public readonly validations: FieldError[],
+	) {
+		super("Parameters are not valid for new template version");
+	}
+}
+
 export type GetProvisionerJobsParams = {
 	status?: string;
 	limit?: number;
@@ -1239,7 +1249,6 @@ class ApiMethods {
 			`/api/v2/workspaces/${workspaceId}/builds`,
 			data,
 		);
-
 		return response.data;
 	};
 
@@ -2268,19 +2277,34 @@ class ApiMethods {
 
 		const activeVersionId = template.active_version_id;
 
-		let templateParameters: TypesGen.TemplateVersionParameter[] = [];
-
 		if (isDynamicParametersEnabled) {
-			templateParameters = await this.getDynamicParameters(
-				activeVersionId,
-				workspace.owner_id,
-				oldBuildParameters,
-			);
-		} else {
-			templateParameters =
-				await this.getTemplateVersionRichParameters(activeVersionId);
+			try {
+				return await this.postWorkspaceBuild(workspace.id, {
+					transition: "start",
+					template_version_id: activeVersionId,
+					rich_parameter_values: newBuildParameters,
+				});
+			} catch (error) {
+				// If the build failed because of a parameter validation error, then we
+				// throw a special sentinel error that can be caught by the caller.
+				if (
+					isApiError(error) &&
+					error.response.status === 400 &&
+					error.response.data.validations &&
+					error.response.data.validations.length > 0
+				) {
+					throw new ParameterValidationError(
+						activeVersionId,
+						error.response.data.validations,
+					);
+				}
+				throw error;
+			}
 		}
 
+		const templateParameters =
+			await this.getTemplateVersionRichParameters(activeVersionId);
+
 		const missingParameters = getMissingParameters(
 			oldBuildParameters,
 			newBuildParameters,
diff --git a/site/src/modules/workspaces/WorkspaceMoreActions/UpdateBuildParametersDialogExperimental.tsx b/site/src/modules/workspaces/WorkspaceMoreActions/UpdateBuildParametersDialogExperimental.tsx
index 04bb92a5e79b2..850f31185af2c 100644
--- a/site/src/modules/workspaces/WorkspaceMoreActions/UpdateBuildParametersDialogExperimental.tsx
+++ b/site/src/modules/workspaces/WorkspaceMoreActions/UpdateBuildParametersDialogExperimental.tsx
@@ -1,4 +1,4 @@
-import type { TemplateVersionParameter } from "api/typesGenerated";
+import type { FieldError } from "api/errors";
 import { Button } from "components/Button/Button";
 import {
 	Dialog,
@@ -14,7 +14,7 @@ import { useNavigate } from "react-router-dom";
 type UpdateBuildParametersDialogExperimentalProps = {
 	open: boolean;
 	onClose: () => void;
-	missedParameters: TemplateVersionParameter[];
+	validations: FieldError[];
 	workspaceOwnerName: string;
 	workspaceName: string;
 	templateVersionId: string | undefined;
@@ -23,7 +23,7 @@ type UpdateBuildParametersDialogExperimentalProps = {
 export const UpdateBuildParametersDialogExperimental: FC<
 	UpdateBuildParametersDialogExperimentalProps
 > = ({
-	missedParameters,
+	validations,
 	open,
 	onClose,
 	workspaceOwnerName,
@@ -47,8 +47,8 @@ export const UpdateBuildParametersDialogExperimental: FC<
 					<DialogDescription>
 						This template has{" "}
 						<strong className="text-content-primary">
-							{missedParameters.length} new parameter
-							{missedParameters.length === 1 ? "" : "s"}
+							{validations.length} parameter
+							{validations.length === 1 ? "" : "s"}
 						</strong>{" "}
 						that must be configured to complete the update.
 					</DialogDescription>
diff --git a/site/src/modules/workspaces/WorkspaceMoreActions/WorkspaceMoreActions.tsx b/site/src/modules/workspaces/WorkspaceMoreActions/WorkspaceMoreActions.tsx
index 3853af67d394f..19d12ab2a394e 100644
--- a/site/src/modules/workspaces/WorkspaceMoreActions/WorkspaceMoreActions.tsx
+++ b/site/src/modules/workspaces/WorkspaceMoreActions/WorkspaceMoreActions.tsx
@@ -1,4 +1,4 @@
-import { MissingBuildParameters } from "api/api";
+import { MissingBuildParameters, ParameterValidationError } from "api/api";
 import { isApiError } from "api/errors";
 import { type ApiError, getErrorMessage } from "api/errors";
 import {
@@ -192,19 +192,19 @@ export const WorkspaceMoreActions: FC<WorkspaceMoreActionsProps> = ({
 				/>
 			) : (
 				<UpdateBuildParametersDialogExperimental
-					missedParameters={
-						changeVersionMutation.error instanceof MissingBuildParameters
-							? changeVersionMutation.error.parameters
+					validations={
+						changeVersionMutation.error instanceof ParameterValidationError
+							? changeVersionMutation.error.validations
 							: []
 					}
-					open={changeVersionMutation.error instanceof MissingBuildParameters}
+					open={changeVersionMutation.error instanceof ParameterValidationError}
 					onClose={() => {
 						changeVersionMutation.reset();
 					}}
 					workspaceOwnerName={workspace.owner_name}
 					workspaceName={workspace.name}
 					templateVersionId={
-						changeVersionMutation.error instanceof MissingBuildParameters
+						changeVersionMutation.error instanceof ParameterValidationError
 							? changeVersionMutation.error?.versionId
 							: undefined
 					}
diff --git a/site/src/modules/workspaces/WorkspaceUpdateDialogs.tsx b/site/src/modules/workspaces/WorkspaceUpdateDialogs.tsx
index bdad9e405bd48..2fad94de2da73 100644
--- a/site/src/modules/workspaces/WorkspaceUpdateDialogs.tsx
+++ b/site/src/modules/workspaces/WorkspaceUpdateDialogs.tsx
@@ -1,4 +1,4 @@
-import { MissingBuildParameters } from "api/api";
+import { MissingBuildParameters, ParameterValidationError } from "api/api";
 import { updateWorkspace } from "api/queries/workspaces";
 import type {
 	TemplateVersion,
@@ -78,7 +78,10 @@ export const useWorkspaceUpdate = ({
 					updateWorkspaceMutation.reset();
 				},
 				onUpdate: (buildParameters: WorkspaceBuildParameter[]) => {
-					if (updateWorkspaceMutation.error instanceof MissingBuildParameters) {
+					if (
+						updateWorkspaceMutation.error instanceof MissingBuildParameters ||
+						updateWorkspaceMutation.error instanceof ParameterValidationError
+					) {
 						confirmUpdate(buildParameters);
 					}
 				},
@@ -154,8 +157,10 @@ const MissingBuildParametersDialog: FC<MissingBuildParametersDialogProps> = ({
 	const missedParameters =
 		error instanceof MissingBuildParameters ? error.parameters : [];
 	const versionId =
-		error instanceof MissingBuildParameters ? error.versionId : undefined;
-	const isOpen = error instanceof MissingBuildParameters;
+		error instanceof ParameterValidationError ? error.versionId : undefined;
+	const isOpen =
+		error instanceof MissingBuildParameters ||
+		error instanceof ParameterValidationError;
 
 	return workspace.template_use_classic_parameter_flow ? (
 		<UpdateBuildParametersDialog
@@ -165,7 +170,9 @@ const MissingBuildParametersDialog: FC<MissingBuildParametersDialogProps> = ({
 		/>
 	) : (
 		<UpdateBuildParametersDialogExperimental
-			missedParameters={missedParameters}
+			validations={
+				error instanceof ParameterValidationError ? error.validations : []
+			}
 			open={isOpen}
 			onClose={dialogProps.onClose}
 			workspaceOwnerName={workspace.owner_name}