diff --git a/src/pages/api/assets/compression/replace.ts b/src/pages/api/assets/compression/replace.ts
index a52f18a..c2b8382 100644
--- a/src/pages/api/assets/compression/replace.ts
+++ b/src/pages/api/assets/compression/replace.ts
@@ -2,10 +2,11 @@ import { ENV } from "@/config/environment";
 import { db } from "@/config/db";
 import { getCurrentUser } from "@/handlers/serverUtils/user.utils";
 import { getUserHeaders } from "@/helpers/user.helper";
-import { clearCompressionDirectory, getCompressionOutputPath, getVideoContentType } from "@/helpers/compression.server";
+import { clearCompressionDirectory, getCompressionOutputPath } from "@/helpers/compression.server";
 import { assets } from "@/schema";
 import { and, eq } from "drizzle-orm";
-import { openAsBlob } from "node:fs";
+import { createReadStream } from "node:fs";
+import { stat } from "node:fs/promises";
 import path from "node:path";
 import type { NextApiRequest, NextApiResponse } from "next";
 
@@ -14,6 +15,24 @@ const readError = async (response: Response) => {
   return body || response.statusText || `HTTP ${response.status}`;
 };
 
+class UploadFile extends File {
+  constructor(
+    private readonly filePath: string,
+    private readonly fileSize: number,
+    fileName: string,
+  ) {
+    super([], fileName);
+  }
+
+  override get size() {
+    return this.fileSize;
+  }
+
+  override stream() {
+    return createReadStream(this.filePath) as any;
+  }
+}
+
 export default async function handler(req: NextApiRequest, res: NextApiResponse) {
   if (req.method !== "POST") return res.status(405).json({ message: "Method not allowed" });
 
@@ -65,18 +84,19 @@ export default async function handler(req: NextApiRequest, res: NextApiResponse)
 
     const replacementFileName = path.basename(source.originalFileName || dbAsset.originalFileName || `${dbAsset.id}.mp4`);
     const outputPath = getCompressionOutputPath(dbAsset.id, dbAsset.originalFileName);
-    const fileBlob = await openAsBlob(outputPath, { type: getVideoContentType(outputPath) });
+    const outputStats = await stat(outputPath);
+    const uploadFile = new UploadFile(outputPath, outputStats.size, replacementFileName);
+
+    // Keep the upload payload aligned with Immich's own CLI uploader.
+    // Restore Power Tools/custom metadata only after Immich has created the asset.
     const formData = new FormData();
     formData.set("fileCreatedAt", source.fileCreatedAt);
     formData.set("fileModifiedAt", source.fileModifiedAt);
+    formData.set("fileSize", String(outputStats.size));
     formData.set("filename", replacementFileName);
-    formData.set("assetData", fileBlob, replacementFileName);
-    if (typeof source.duration === "number") formData.set("duration", String(source.duration));
+    formData.set("isFavorite", source.isFavorite ? "true" : "false");
+    formData.set("assetData", uploadFile, replacementFileName);
     if (source.visibility) formData.set("visibility", source.visibility);
-    if (source.isFavorite) formData.set("isFavorite", "true");
-    if (Array.isArray(customMetadata) && customMetadata.length > 0) {
-      formData.set("metadata", JSON.stringify(customMetadata.map(({ key, value }: any) => ({ key, value }))));
-    }
 
     const { ["Content-Type"]: _contentType, ...uploadHeaders } = jsonHeaders;
     const uploadResponse = await fetch(`${ENV.IMMICH_URL}/api/assets`, {
@@ -84,7 +104,13 @@ export default async function handler(req: NextApiRequest, res: NextApiResponse)
       headers: uploadHeaders,
       body: formData,
     });
-    if (!uploadResponse.ok) throw new Error(`Failed to upload compressed asset: ${await readError(uploadResponse)}`);
+    if (!uploadResponse.ok) {
+      const details = await readError(uploadResponse);
+      if (uploadResponse.status === 403) {
+        throw new Error(`Immich rejected the upload (403). The configured API key/session needs asset.upload permission. ${details}`);
+      }
+      throw new Error(`Failed to upload compressed asset (${uploadResponse.status}): ${details}`);
+    }
 
     const uploaded = await uploadResponse.json();
     if (!uploaded?.id) throw new Error("Immich upload response did not include an asset id");
@@ -95,6 +121,23 @@ export default async function handler(req: NextApiRequest, res: NextApiResponse)
     newAssetId = uploaded.id;
     createdNewAsset = true;
 
+    if (Array.isArray(customMetadata) && customMetadata.length > 0) {
+      const metadataItems = customMetadata
+        .filter((item: any) => item?.key && item?.value && typeof item.value === "object")
+        .map(({ key, value }: any) => ({ key, value }));
+
+      if (metadataItems.length > 0) {
+        const customMetadataResponse = await fetch(`${ENV.IMMICH_URL}/api/assets/${newAssetId}/metadata`, {
+          method: "PUT",
+          headers: jsonHeaders,
+          body: JSON.stringify({ items: metadataItems }),
+        });
+        if (!customMetadataResponse.ok) {
+          throw new Error(`Failed to restore custom metadata: ${await readError(customMetadataResponse)}`);
+        }
+      }
+    }
+
     const copyResponse = await fetch(`${ENV.IMMICH_URL}/api/assets/copy`, {
       method: "PUT",
       headers: jsonHeaders,
@@ -186,6 +229,11 @@ export default async function handler(req: NextApiRequest, res: NextApiResponse)
       fileName: replacementFileName,
     });
   } catch (error: any) {
+    console.error("[compression:replace]", {
+      assetId: dbAsset.id,
+      message: error?.message,
+      stack: error?.stack,
+    });
     if (rollbackSafe && changedLivePhotoParentIds.length > 0) {
       await Promise.all(changedLivePhotoParentIds.map((parentId) =>
         fetch(`${ENV.IMMICH_URL}/api/assets/${parentId}`, {