diff --git a/web-demo/src/components/inventory/UploadTemplateDialog.tsx b/web-demo/src/components/inventory/UploadTemplateDialog.tsx
index 43ff3a0..bb00dd5 100644
--- a/web-demo/src/components/inventory/UploadTemplateDialog.tsx
+++ b/web-demo/src/components/inventory/UploadTemplateDialog.tsx
@@ -17,7 +17,13 @@ import { api, ApiError, type ClusterResource, type Storage } from "@/lib/api"
 async function uploadFile(path: string, form: FormData): Promise<{ upid: string }> {
   const res = await fetch(`/api/v1${path}`, { method: "POST", body: form, credentials: "include" })
   const data = await res.json().catch(() => undefined)
-  if (!res.ok) throw new ApiError(res.status, data?.error ?? res.statusText, data?.code)
+  if (!res.ok) {
+    throw new ApiError(
+      res.status,
+      (typeof data?.error === "string" && data.error) || res.statusText || `Request failed (HTTP ${res.status})`,
+      data?.code,
+    )
+  }
   return data
 }
 
diff --git a/web-demo/src/lib/api.ts b/web-demo/src/lib/api.ts
index dc970e7..fc22442 100644
--- a/web-demo/src/lib/api.ts
+++ b/web-demo/src/lib/api.ts
@@ -55,7 +55,15 @@ async function request<T>(path: string, init?: RequestInit): Promise<T> {
     if (data?.code) {
       for (const handler of errorCodeHandlers) handler(data.code)
     }
-    throw new ApiError(res.status, data?.error ?? res.statusText, data?.code)
+    // `||` (not ??) so empty values fall through: statusText is "" over
+    // HTTP/2, and an empty message renders as an icon-only toast. The typeof
+    // guard keeps a non-string `error` (e.g. an OpenAI-style object from a
+    // proxy) from becoming "[object Object]".
+    throw new ApiError(
+      res.status,
+      (typeof data?.error === "string" && data.error) || res.statusText || `Request failed (HTTP ${res.status})`,
+      data?.code,
+    )
   }
   return data as T
 }
diff --git a/web/src/components/inventory/UploadTemplateDialog.tsx b/web/src/components/inventory/UploadTemplateDialog.tsx
index fb066a0..7af0506 100644
--- a/web/src/components/inventory/UploadTemplateDialog.tsx
+++ b/web/src/components/inventory/UploadTemplateDialog.tsx
@@ -17,7 +17,13 @@ import { api, ApiError, type ClusterResource, type Storage } from "@/lib/api"
 async function uploadFile(path: string, form: FormData): Promise<{ upid: string }> {
   const res = await fetch(`/api/v1${path}`, { method: "POST", body: form, credentials: "include" })
   const data = await res.json().catch(() => undefined)
-  if (!res.ok) throw new ApiError(res.status, data?.error ?? res.statusText, data?.code)
+  if (!res.ok) {
+    throw new ApiError(
+      res.status,
+      (typeof data?.error === "string" && data.error) || res.statusText || `Request failed (HTTP ${res.status})`,
+      data?.code,
+    )
+  }
   return data
 }
 
diff --git a/web/src/lib/api.ts b/web/src/lib/api.ts
index 13dcd5c..113d981 100644
--- a/web/src/lib/api.ts
+++ b/web/src/lib/api.ts
@@ -63,7 +63,15 @@ async function request<T>(path: string, init?: RequestInit): Promise<T> {
     if (data?.code) {
       for (const handler of errorCodeHandlers) handler(data.code)
     }
-    throw new ApiError(res.status, data?.error ?? res.statusText, data?.code)
+    // `||` (not ??) so empty values fall through: statusText is "" over
+    // HTTP/2, and an empty message renders as an icon-only toast. The typeof
+    // guard keeps a non-string `error` (e.g. an OpenAI-style object from a
+    // proxy) from becoming "[object Object]".
+    throw new ApiError(
+      res.status,
+      (typeof data?.error === "string" && data.error) || res.statusText || `Request failed (HTTP ${res.status})`,
+      data?.code,
+    )
   }
   return data as T
 }