diff --git a/web/src/api/queries.ts b/web/src/api/queries.ts
index 6be8c8b..5e727ea 100644
--- a/web/src/api/queries.ts
+++ b/web/src/api/queries.ts
@@ -179,9 +179,9 @@ export function useCreateObject() {
 
   return useMutation({
     mutationFn: async (body: ObjectCreateRequest) => {
-      const { data, error } = await api.POST("/api/admin/objects", { body });
+      const { data, error, response } = await api.POST("/api/admin/objects", { body });
 
-      if (error || !data) throw new Error("create failed");
+      if (error || !data) throw new HttpError(response.status);
 
       return data;
     },
@@ -200,7 +200,7 @@ export function useUpdateObject() {
         body,
       });
 
-      if (response.status !== 204) throw new Error("update failed");
+      if (response.status !== 204) throw new HttpError(response.status);
     },
     onSuccess: (_d, { id }) => {
       void qc.invalidateQueries({ queryKey: ["objects"] });
@@ -227,7 +227,7 @@ export function useSetFields() {
         throw new FieldRejection(detail.field, detail.code);
       }
 
-      throw new Error("set fields failed");
+      throw new HttpError(response.status);
     },
     onSuccess: (_d, { id }) => {
       void qc.invalidateQueries({ queryKey: ["object", id] });
@@ -245,7 +245,7 @@ export function useDeleteObject() {
         params: { path: { id } },
       });
 
-      if (response.status !== 204) throw new Error("delete failed");
+      if (response.status !== 204) throw new HttpError(response.status);
     },
     onSuccess: () => qc.invalidateQueries({ queryKey: ["objects"] }),
     meta: { successMessage: "toast.deleted", suppressErrorToast: true },
@@ -274,9 +274,9 @@ export function useCreateVocabulary() {
 
   return useMutation({
     mutationFn: async (body: NewVocabularyRequest) => {
-      const { data, error } = await api.POST("/api/admin/vocabularies", { body });
+      const { data, error, response } = await api.POST("/api/admin/vocabularies", { body });
 
-      if (error || !data) throw new Error("create vocabulary failed");
+      if (error || !data) throw new HttpError(response.status);
 
       return data;
     },
@@ -303,7 +303,7 @@ export function useAddTerm() {
         body: { external_uri, labels },
       });
 
-      if (response.status !== 201) throw new Error("add term failed");
+      if (response.status !== 201) throw new HttpError(response.status);
     },
     onSuccess: (_result, { vocabularyId }) =>
       qc.invalidateQueries({ queryKey: ["terms", vocabularyId] }),
@@ -328,7 +328,7 @@ export function useCreateAuthority() {
         body: { kind, external_uri, labels },
       });
 
-      if (response.status !== 201) throw new Error("create authority failed");
+      if (response.status !== 201) throw new HttpError(response.status);
     },
     onSuccess: (_result, { kind }) =>
       qc.invalidateQueries({ queryKey: ["authorities", kind] }),
@@ -379,7 +379,7 @@ export function useCreateFieldDefinition() {
     mutationFn: async (body: NewFieldDefinitionRequest) => {
       const { data, response } = await api.POST("/api/admin/field-definitions", { body });
 
-      if (response.status !== 201 || !data) throw new Error("failed to create field definition");
+      if (response.status !== 201 || !data) throw new HttpError(response.status);
 
       return data;
     },
@@ -438,7 +438,7 @@ export function useUpdateTerm() {
         body: { external_uri, labels },
       });
 
-      if (response.status !== 204) throw new Error("update term failed");
+      if (response.status !== 204) throw new HttpError(response.status);
     },
     onSuccess: (_d, { vocabularyId }) => qc.invalidateQueries({ queryKey: ["terms", vocabularyId] }),
     meta: { successMessage: "toast.saved" },
@@ -455,7 +455,7 @@ export function useDeleteTerm() {
       });
 
       if (response.status === 409) throw new InUseError((error as { count?: number })?.count ?? 0);
-      if (response.status !== 204) throw new Error("delete term failed");
+      if (response.status !== 204) throw new HttpError(response.status);
     },
     onSuccess: (_d, { vocabularyId }) => qc.invalidateQueries({ queryKey: ["terms", vocabularyId] }),
     meta: { successMessage: "toast.deleted", suppressErrorToast: true },
@@ -472,7 +472,7 @@ export function useRenameVocabulary() {
         body: { key },
       });
 
-      if (response.status !== 204) throw new Error("rename failed");
+      if (response.status !== 204) throw new HttpError(response.status);
     },
     onSuccess: () => qc.invalidateQueries({ queryKey: ["vocabularies"] }),
     meta: { successMessage: "toast.renamed", suppressErrorToast: true },
@@ -489,7 +489,7 @@ export function useDeleteVocabulary() {
       });
 
       if (response.status === 409) throw new InUseError((error as { count?: number })?.count ?? 0);
-      if (response.status !== 204) throw new Error("delete vocabulary failed");
+      if (response.status !== 204) throw new HttpError(response.status);
     },
     onSuccess: () => qc.invalidateQueries({ queryKey: ["vocabularies"] }),
     meta: { successMessage: "toast.deleted", suppressErrorToast: true },
@@ -515,7 +515,7 @@ export function useUpdateAuthority() {
         body: { external_uri, labels },
       });
 
-      if (response.status !== 204) throw new Error("update authority failed");
+      if (response.status !== 204) throw new HttpError(response.status);
     },
     onSuccess: (_d, { kind }) => qc.invalidateQueries({ queryKey: ["authorities", kind] }),
     meta: { successMessage: "toast.saved" },
@@ -532,7 +532,7 @@ export function useDeleteAuthority() {
       });
 
       if (response.status === 409) throw new InUseError((error as { count?: number })?.count ?? 0);
-      if (response.status !== 204) throw new Error("delete authority failed");
+      if (response.status !== 204) throw new HttpError(response.status);
     },
     onSuccess: (_d, { kind }) => qc.invalidateQueries({ queryKey: ["authorities", kind] }),
     meta: { successMessage: "toast.deleted", suppressErrorToast: true },
@@ -559,7 +559,7 @@ export function useUpdateFieldDefinition() {
         body: { required, group, labels },
       });
 
-      if (response.status !== 204) throw new Error("update field failed");
+      if (response.status !== 204) throw new HttpError(response.status);
     },
     onSuccess: () => qc.invalidateQueries({ queryKey: ["field-definitions"] }),
     meta: { successMessage: "toast.saved", suppressErrorToast: true },
@@ -576,7 +576,7 @@ export function useDeleteFieldDefinition() {
       });
 
       if (response.status === 409) throw new InUseError((error as { count?: number })?.count ?? 0);
-      if (response.status !== 204) throw new Error("delete field failed");
+      if (response.status !== 204) throw new HttpError(response.status);
     },
     onSuccess: () => qc.invalidateQueries({ queryKey: ["field-definitions"] }),
     meta: { successMessage: "toast.deleted", suppressErrorToast: true },