diff --git a/keyserver/src/services/blob.js b/keyserver/src/services/blob.js
--- a/keyserver/src/services/blob.js
+++ b/keyserver/src/services/blob.js
@@ -5,6 +5,7 @@
 import {
   makeBlobServiceEndpointURL,
   downloadBlob,
+  assignBlobHolder,
 } from 'lib/utils/blob-service.js';
 import {
   uploadBlob,
@@ -44,26 +45,9 @@
 async function assignHolder(
   params: BlobDescriptor,
 ): Promise<BlobOperationResult> {
-  const { hash, holder } = params;
+  const { hash: blobHash, holder } = params;
   const headers = await createRequestHeaders();
-  const assignHolderResponse = await fetch(
-    makeBlobServiceEndpointURL(blobService.httpEndpoints.ASSIGN_HOLDER),
-    {
-      method: blobService.httpEndpoints.ASSIGN_HOLDER.method,
-      body: JSON.stringify({
-        holder,
-        blob_hash: hash,
-      }),
-      headers,
-    },
-  );
-
-  if (!assignHolderResponse.ok) {
-    const { status, statusText } = assignHolderResponse;
-    return { success: false, reason: 'OTHER', status, statusText };
-  }
-
-  return { success: true };
+  return assignBlobHolder({ blobHash, holder }, headers);
 }
 
 async function uploadBlobKeyserverWrapper(
diff --git a/lib/actions/upload-actions.js b/lib/actions/upload-actions.js
--- a/lib/actions/upload-actions.js
+++ b/lib/actions/upload-actions.js
@@ -28,13 +28,11 @@
   makeBlobServiceEndpointURL,
   makeBlobServiceURI,
   generateBlobHolder,
+  assignBlobHolder,
 } from '../utils/blob-service.js';
 import { getMessageForException } from '../utils/errors.js';
 import { useDispatch } from '../utils/redux-utils.js';
-import {
-  handleHTTPResponseError,
-  createDefaultHTTPRequestHeaders,
-} from '../utils/services-utils.js';
+import { createDefaultHTTPRequestHeaders } from '../utils/services-utils.js';
 
 export type MultimediaUploadCallbacks = Partial<{
   +onProgress: (percent: number) => void,
@@ -126,24 +124,16 @@
     // 1. Assign new holder for blob with given blobHash
     let blobAlreadyExists: boolean;
     try {
-      const assignHolderEndpoint = blobService.httpEndpoints.ASSIGN_HOLDER;
-      const assignHolderResponse = await fetch(
-        makeBlobServiceEndpointURL(assignHolderEndpoint),
-        {
-          method: assignHolderEndpoint.method,
-          body: JSON.stringify({
-            holder: blobHolder,
-            blob_hash: blobHash,
-          }),
-          headers: {
-            ...defaultHeaders,
-            'content-type': 'application/json',
-          },
-        },
+      const assignHolderResult = await assignBlobHolder(
+        { blobHash, holder: blobHolder },
+        defaultHeaders,
       );
-      handleHTTPResponseError(assignHolderResponse);
+      if (!assignHolderResult.success) {
+        const { status, statusText } = assignHolderResult;
+        throw new Error(`Server responded with HTTP ${status}: ${statusText}`);
+      }
       const { data_exists: dataExistsResponse } =
-        await assignHolderResponse.json();
+        await assignHolderResult.response.json();
       blobAlreadyExists = dataExistsResponse;
     } catch (e) {
       throw new Error(
@@ -303,22 +293,14 @@
 
     // 1. Assign new holder for blob with given blobHash
     try {
-      const assignHolderEndpoint = blobService.httpEndpoints.ASSIGN_HOLDER;
-      const assignHolderResponse = await fetch(
-        makeBlobServiceEndpointURL(assignHolderEndpoint),
-        {
-          method: assignHolderEndpoint.method,
-          body: JSON.stringify({
-            holder: blobHolder,
-            blob_hash: blobHash,
-          }),
-          headers: {
-            ...defaultHeaders,
-            'content-type': 'application/json',
-          },
-        },
+      const assignHolderResult = await assignBlobHolder(
+        { blobHash, holder: blobHolder },
+        defaultHeaders,
       );
-      handleHTTPResponseError(assignHolderResponse);
+      if (!assignHolderResult.success) {
+        const { status, statusText } = assignHolderResult;
+        throw new Error(`Server responded with HTTP ${status}: ${statusText}`);
+      }
     } catch (e) {
       throw new Error(
         `Failed to assign holder: ${
diff --git a/lib/utils/blob-service.js b/lib/utils/blob-service.js
--- a/lib/utils/blob-service.js
+++ b/lib/utils/blob-service.js
@@ -75,6 +75,7 @@
 export type BlobOperationResult =
   | {
       +success: true,
+      +response: Response,
     }
   | {
       +success: false,
@@ -139,7 +140,35 @@
     };
   }
 
-  return { success: true };
+  return { success: true, response: uploadBlobResponse };
+}
+
+async function assignBlobHolder(
+  blobInfo: BlobInfo,
+  headers: { [string]: string },
+): Promise<BlobOperationResult> {
+  const { blobHash, holder } = blobInfo;
+  const response = await fetch(
+    makeBlobServiceEndpointURL(blobServiceConfig.httpEndpoints.ASSIGN_HOLDER),
+    {
+      method: blobServiceConfig.httpEndpoints.ASSIGN_HOLDER.method,
+      body: JSON.stringify({
+        holder,
+        blob_hash: blobHash,
+      }),
+      headers: {
+        ...headers,
+        'content-type': 'application/json',
+      },
+    },
+  );
+
+  if (!response.ok) {
+    const { status, statusText } = response;
+    return { success: false, reason: 'OTHER', status, statusText };
+  }
+
+  return { success: true, response };
 }
 
 async function assignMultipleHolders(
@@ -243,6 +272,7 @@
   makeBlobServiceEndpointURL,
   downloadBlob,
   uploadBlob,
+  assignBlobHolder,
   assignMultipleHolders,
   removeMultipleHolders,
 };
diff --git a/lib/utils/services-utils.js b/lib/utils/services-utils.js
--- a/lib/utils/services-utils.js
+++ b/lib/utils/services-utils.js
@@ -23,13 +23,6 @@
 // (secondary login).
 const usingRestoreFlow = false;
 
-function handleHTTPResponseError(response: Response): void {
-  if (!response.ok) {
-    const { status, statusText } = response;
-    throw new Error(`Server responded with HTTP ${status}: ${statusText}`);
-  }
-}
-
 function createHTTPAuthorizationHeader(authMetadata: AuthMetadata): string {
   // explicit destructure to make it future-proof
   const { userID, deviceID, accessToken } = authMetadata;
@@ -48,7 +41,6 @@
 }
 
 export {
-  handleHTTPResponseError,
   usingCommServicesAccessToken,
   supportingMultipleKeyservers,
   relyingOnAuthoritativeKeyserver,