diff --git a/packages/server/src/adapter/sveltekit/handler.ts b/packages/server/src/adapter/sveltekit/handler.ts
index 355f7ee5..84eb14bb 100644
--- a/packages/server/src/adapter/sveltekit/handler.ts
+++ b/packages/server/src/adapter/sveltekit/handler.ts
@@ -1,4 +1,4 @@
-import type { Handle, RequestEvent } from '@sveltejs/kit';
+import { type Handle, type RequestEvent } from '@sveltejs/kit';
 import type { ClientContract } from '@zenstackhq/orm';
 import type { SchemaDef } from '@zenstackhq/orm/schema';
 import { logInternalError, type CommonAdapterOptions } from '../common';
@@ -37,9 +37,18 @@ export default function createHandler<Schema extends SchemaDef>(options: SvelteK
             const query = Object.fromEntries(event.url.searchParams);
             let requestBody: unknown;
             if (event.request.body) {
-                const text = await event.request.text();
-                if (text) {
-                    requestBody = JSON.parse(text);
+                try {
+                    const text = await event.request.text();
+                    if (text) {
+                        requestBody = JSON.parse(text);
+                    }
+                } catch {
+                    return new Response(JSON.stringify({ message: 'invalid JSON payload' }), {
+                        status: 400,
+                        headers: {
+                            'content-type': 'application/json',
+                        },
+                    });
                 }
             }
 
diff --git a/packages/server/test/adapter/fastify.test.ts b/packages/server/test/adapter/fastify.test.ts
index 85c0a463..d5d2be6b 100644
--- a/packages/server/test/adapter/fastify.test.ts
+++ b/packages/server/test/adapter/fastify.test.ts
@@ -146,7 +146,7 @@ describe('Fastify adapter tests - rest handler', () => {
         app.register(ZenStackFastifyPlugin, {
             prefix: '/api',
             getClient: () => client,
-            apiHandler: new RestApiHandler({ schema: client.schema, endpoint: 'http://localhost/api' }),
+            apiHandler: new RestApiHandler({ schema: client.$schema, endpoint: 'http://localhost/api' }),
         });
 
         let r = await app.inject({
diff --git a/packages/server/test/adapter/tanstack-start.test.ts b/packages/server/test/adapter/tanstack-start.test.ts
index 1fb83a25..4d4031ef 100644
--- a/packages/server/test/adapter/tanstack-start.test.ts
+++ b/packages/server/test/adapter/tanstack-start.test.ts
@@ -89,7 +89,7 @@ model M {
         const db = await createTestClient(model);
         const options: TanStackStartOptions<SchemaDef> = {
             getClient: () => db,
-            apiHandler: new RPCApiHandler({ schema: db.schema }),
+            apiHandler: new RPCApiHandler({ schema: db.$schema }),
         };
 
         const client = await makeTestClient('/m/create', options)
@@ -179,7 +179,7 @@ model M {
         const db = await createPolicyTestClient(model);
         const options: TanStackStartOptions<SchemaDef> = {
             getClient: () => db,
-            apiHandler: new RPCApiHandler({ schema: db.schema }),
+            apiHandler: new RPCApiHandler({ schema: db.$schema }),
         };
 
         const createForbidden = await makeTestClient('/m/create', options)
@@ -233,7 +233,7 @@ model M {
 
         const options: TanStackStartOptions<SchemaDef> = {
             getClient: () => db,
-            apiHandler: new RestApiHandler({ endpoint: 'http://localhost/api', schema: db.schema }),
+            apiHandler: new RestApiHandler({ endpoint: 'http://localhost/api', schema: db.$schema }),
         };
 
         const create = await makeTestClient('/m', options)