diff --git a/server/upload.go b/server/upload.go
index ddf4321d..aecddfbb 100644
--- a/server/upload.go
+++ b/server/upload.go
@@ -95,6 +95,7 @@ func (b *blobUpload) Prepare(ctx context.Context, requestURL *url.URL, opts *Reg
 			size = fi.Size() - offset
 		}
 
+		// set part.N to the current number of parts
 		b.Parts = append(b.Parts, blobUploadPart{N: len(b.Parts), Offset: offset, Size: size})
 		offset += size
 	}
@@ -111,22 +112,22 @@ func (b *blobUpload) Prepare(ctx context.Context, requestURL *url.URL, opts *Reg
 	return nil
 }
 
+// Run uploads blob parts to the upstream. If the upstream supports redirection, parts will be uploaded
+// in parallel as defined by Prepare. Otherwise, parts will be uploaded serially. Run sets b.err on error.
 func (b *blobUpload) Run(ctx context.Context, opts *RegistryOptions) {
-	b.err = b.run(ctx, opts)
-}
-
-func (b *blobUpload) run(ctx context.Context, opts *RegistryOptions) error {
 	defer blobUploadManager.Delete(b.Digest)
 	ctx, b.CancelFunc = context.WithCancel(ctx)
 
 	p, err := GetBlobsPath(b.Digest)
 	if err != nil {
-		return err
+		b.err = err
+		return
 	}
 
 	f, err := os.Open(p)
 	if err != nil {
-		return err
+		b.err = err
+		return
 	}
 	defer f.Close()
 
@@ -134,30 +135,34 @@ func (b *blobUpload) run(ctx context.Context, opts *RegistryOptions) error {
 	g.SetLimit(numUploadParts)
 	for i := range b.Parts {
 		part := &b.Parts[i]
-		requestURL := <-b.nextURL
-		g.Go(func() error {
-			for try := 0; try < maxRetries; try++ {
-				r := io.NewSectionReader(f, part.Offset, part.Size)
-				err := b.uploadChunk(inner, http.MethodPatch, requestURL, r, part, opts)
-				switch {
-				case errors.Is(err, context.Canceled):
-					return err
-				case errors.Is(err, errMaxRetriesExceeded):
-					return err
-				case err != nil:
-					log.Printf("%s part %d attempt %d failed: %v, retrying", b.Digest[7:19], part.N, try, err)
-					continue
+		select {
+		case <-inner.Done():
+		case requestURL := <-b.nextURL:
+			g.Go(func() error {
+				for try := 0; try < maxRetries; try++ {
+					r := io.NewSectionReader(f, part.Offset, part.Size)
+					err := b.uploadChunk(inner, http.MethodPatch, requestURL, r, part, opts)
+					switch {
+					case errors.Is(err, context.Canceled):
+						return err
+					case errors.Is(err, errMaxRetriesExceeded):
+						return err
+					case err != nil:
+						log.Printf("%s part %d attempt %d failed: %v, retrying", b.Digest[7:19], part.N, try, err)
+						continue
+					}
+
+					return nil
 				}
 
-				return nil
-			}
-
-			return errMaxRetriesExceeded
-		})
+				return errMaxRetriesExceeded
+			})
+		}
 	}
 
 	if err := g.Wait(); err != nil {
-		return err
+		b.err = err
+		return
 	}
 
 	requestURL := <-b.nextURL
@@ -172,12 +177,12 @@ func (b *blobUpload) run(ctx context.Context, opts *RegistryOptions) error {
 
 	resp, err := makeRequest(ctx, "PUT", requestURL, headers, nil, opts)
 	if err != nil {
-		return err
+		b.err = err
+		return
 	}
 	defer resp.Body.Close()
 
 	b.done = true
-	return nil
 }
 
 func (b *blobUpload) uploadChunk(ctx context.Context, method string, requestURL *url.URL, rs io.ReadSeeker, part *blobUploadPart, opts *RegistryOptions) error {
@@ -219,6 +224,7 @@ func (b *blobUpload) uploadChunk(ctx context.Context, method string, requestURL
 		for try := 0; try < maxRetries; try++ {
 			rs.Seek(0, io.SeekStart)
 			b.Completed.Add(-buw.written)
+			buw.written = 0
 			err := b.uploadChunk(ctx, http.MethodPut, redirectURL, rs, part, nil)
 			switch {
 			case errors.Is(err, context.Canceled):
@@ -253,6 +259,7 @@ func (b *blobUpload) uploadChunk(ctx context.Context, method string, requestURL
 
 		rs.Seek(0, io.SeekStart)
 		b.Completed.Add(-buw.written)
+		buw.written = 0
 		return fmt.Errorf("http status %d %s: %s", resp.StatusCode, resp.Status, body)
 	}