diff --git a/.changeset/eight-wombats-drop.md b/.changeset/eight-wombats-drop.md
new file mode 100644
index 0000000..49fcbb9
--- /dev/null
+++ b/.changeset/eight-wombats-drop.md
@@ -0,0 +1,5 @@
+---
+"@saleor/app-sdk": patch
+---
+
+Fix serialization of the nested values in the UpstashAPL.
diff --git a/src/APL/upstash-apl.test.ts b/src/APL/upstash-apl.test.ts
index a812839..03268a4 100644
--- a/src/APL/upstash-apl.test.ts
+++ b/src/APL/upstash-apl.test.ts
@@ -57,8 +57,7 @@ describe("APL", () => {
           "https://example.com",
 
           {
-            // eslint-disable-next-line quotes
-            body: `["SET", "${stubAuthData.saleorApiUrl}", "${JSON.stringify(stubAuthData)}"]`,
+            body: JSON.stringify(["SET", stubAuthData.saleorApiUrl, JSON.stringify(stubAuthData)]),
             headers: {
               "Content-Type": "application/json",
               Authorization: "Bearer token",
diff --git a/src/APL/upstash-apl.ts b/src/APL/upstash-apl.ts
index 5ff7db7..f64e64a 100644
--- a/src/APL/upstash-apl.ts
+++ b/src/APL/upstash-apl.ts
@@ -54,7 +54,7 @@ export class UpstashAPL implements APL {
     this.restToken = restToken;
   }
 
-  private async upstashRequest(requestBody: string) {
+  private async upstashRequest(request: string[]) {
     debug("Sending request to Upstash");
     if (!this.restURL || !this.restToken) {
       throw new Error(
@@ -66,7 +66,7 @@ export class UpstashAPL implements APL {
       response = await fetch(this.restURL, {
         method: "POST",
         headers: { "Content-Type": "application/json", Authorization: `Bearer ${this.restToken}` },
-        body: requestBody,
+        body: JSON.stringify(request),
       });
     } catch (error) {
       debug("Error during sending the data:", error);
@@ -97,17 +97,17 @@ export class UpstashAPL implements APL {
     });
 
     const data = JSON.stringify(authData);
-    await this.upstashRequest(`["SET", "${authData.saleorApiUrl}", "${data}"]`);
+    await this.upstashRequest(["SET", authData.saleorApiUrl, data]);
   }
 
   private async deleteDataFromUpstash(saleorApiUrl: string) {
-    await this.upstashRequest(`["DEL", "${saleorApiUrl}"]`);
+    await this.upstashRequest(["DEL", saleorApiUrl]);
   }
 
   private async fetchDataFromUpstash(saleorApiUrl: string) {
-    const result = await this.upstashRequest(`["GET", "${saleorApiUrl}"]`);
+    const result = await this.upstashRequest(["GET", saleorApiUrl]);
     if (result) {
-      const authData = JSON.parse(result);
+      const authData = JSON.parse(result) as AuthData;
       return authData;
     }
     return undefined;