From 69294b17b87554211fc5b7e8eef89eca488cfd3d Mon Sep 17 00:00:00 2001
From: beyondkmp <beyondkmp@gmail.com>
Date: Wed, 18 Jun 2025 14:20:36 +0800
Subject: [PATCH 01/10] feat(updater): add support for old block map file URL
 in blockmapFiles function

- Introduced `oldBlockMapFileBaseUrl` property in AppUpdater class to specify the base URL for the old block map file.
- Updated `blockmapFiles` function to accept an optional `oldBlockMapFileBaseUrl` parameter, allowing for more flexible block map URL generation.
---
 packages/electron-updater/src/AppUpdater.ts |  8 +++++++-
 packages/electron-updater/src/util.ts       | 11 +++++++++--
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/packages/electron-updater/src/AppUpdater.ts b/packages/electron-updater/src/AppUpdater.ts
index e239b4c9a16..046943e31c7 100644
--- a/packages/electron-updater/src/AppUpdater.ts
+++ b/packages/electron-updater/src/AppUpdater.ts
@@ -117,6 +117,12 @@ export abstract class AppUpdater extends (EventEmitter as new () => TypedEmitter
    */
   forceDevUpdateConfig = false
 
+  /**
+   * The base URL of the old block map file.
+   * @default null
+   */
+  oldBlockMapFileBaseUrl: string | null = null
+
   /**
    * The current application version.
    */
@@ -790,7 +796,7 @@ export abstract class AppUpdater extends (EventEmitter as new () => TypedEmitter
       if (this._testOnlyOptions != null && !this._testOnlyOptions.isUseDifferentialDownload) {
         return true
       }
-      const blockmapFileUrls = blockmapFiles(fileInfo.url, this.app.version, downloadUpdateOptions.updateInfoAndProvider.info.version)
+      const blockmapFileUrls = blockmapFiles(fileInfo.url, this.app.version, downloadUpdateOptions.updateInfoAndProvider.info.version, this.oldBlockMapFileBaseUrl)
       this._logger.info(`Download block maps (old: "${blockmapFileUrls[0]}", new: ${blockmapFileUrls[1]})`)
 
       const downloadBlockMap = async (url: URL): Promise<BlockMap> => {
diff --git a/packages/electron-updater/src/util.ts b/packages/electron-updater/src/util.ts
index 2216e3ac9fa..5580edff25d 100644
--- a/packages/electron-updater/src/util.ts
+++ b/packages/electron-updater/src/util.ts
@@ -30,8 +30,15 @@ export function getChannelFilename(channel: string): string {
   return `${channel}.yml`
 }
 
-export function blockmapFiles(baseUrl: URL, oldVersion: string, newVersion: string): URL[] {
+export function blockmapFiles(baseUrl: URL, oldVersion: string, newVersion: string, oldBlockMapFileBaseUrl: string | null=null): URL[] {
   const newBlockMapUrl = newUrlFromBase(`${baseUrl.pathname}.blockmap`, baseUrl)
-  const oldBlockMapUrl = newUrlFromBase(`${baseUrl.pathname.replace(new RegExp(escapeRegExp(newVersion), "g"), oldVersion)}.blockmap`, baseUrl)
+
+  let oldBlockMapUrl: URL | null = null
+  if (oldBlockMapFileBaseUrl) {
+   oldBlockMapUrl = new URL(`${oldBlockMapFileBaseUrl}.blockmap` )
+  } else {
+    oldBlockMapUrl = newUrlFromBase(`${baseUrl.pathname.replace(new RegExp(escapeRegExp(newVersion), "g"), oldVersion)}.blockmap`, baseUrl)
+  }
+  
   return [oldBlockMapUrl, newBlockMapUrl]
 }

From 752a6b9382e6f2df0ef08ff759691094595b5394 Mon Sep 17 00:00:00 2001
From: beyondkmp <beyondkmp@gmail.com>
Date: Wed, 18 Jun 2025 14:38:19 +0800
Subject: [PATCH 02/10] format code

---
 packages/dmg-builder/src/dmg.ts       | 14 +++++++-------
 packages/electron-updater/src/util.ts |  6 +++---
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/packages/dmg-builder/src/dmg.ts b/packages/dmg-builder/src/dmg.ts
index 30124bd0889..baee165fa15 100644
--- a/packages/dmg-builder/src/dmg.ts
+++ b/packages/dmg-builder/src/dmg.ts
@@ -206,13 +206,13 @@ async function createStageDmg(tempDmg: string, appPath: string, volumeName: stri
   imageArgs.push("-fs", "APFS")
   imageArgs.push(tempDmg)
   await hdiUtil(imageArgs).catch(async e => {
-      if (hdiutilTransientExitCodes.has(e.code)) {
-        // Delay then create, then retry with verbose output
-        await new Promise(resolve => setTimeout(resolve, 3000))
-        return hdiUtil(addLogLevel(createArgs, true))
-      }
-      throw e
-    })
+    if (hdiutilTransientExitCodes.has(e.code)) {
+      // Delay then create, then retry with verbose output
+      await new Promise(resolve => setTimeout(resolve, 3000))
+      return hdiUtil(addLogLevel(createArgs, true))
+    }
+    throw e
+  })
   return tempDmg
 }
 
diff --git a/packages/electron-updater/src/util.ts b/packages/electron-updater/src/util.ts
index 5580edff25d..571cb59723d 100644
--- a/packages/electron-updater/src/util.ts
+++ b/packages/electron-updater/src/util.ts
@@ -30,15 +30,15 @@ export function getChannelFilename(channel: string): string {
   return `${channel}.yml`
 }
 
-export function blockmapFiles(baseUrl: URL, oldVersion: string, newVersion: string, oldBlockMapFileBaseUrl: string | null=null): URL[] {
+export function blockmapFiles(baseUrl: URL, oldVersion: string, newVersion: string, oldBlockMapFileBaseUrl: string | null = null): URL[] {
   const newBlockMapUrl = newUrlFromBase(`${baseUrl.pathname}.blockmap`, baseUrl)
 
   let oldBlockMapUrl: URL | null = null
   if (oldBlockMapFileBaseUrl) {
-   oldBlockMapUrl = new URL(`${oldBlockMapFileBaseUrl}.blockmap` )
+    oldBlockMapUrl = new URL(`${oldBlockMapFileBaseUrl}.blockmap`)
   } else {
     oldBlockMapUrl = newUrlFromBase(`${baseUrl.pathname.replace(new RegExp(escapeRegExp(newVersion), "g"), oldVersion)}.blockmap`, baseUrl)
   }
-  
+
   return [oldBlockMapUrl, newBlockMapUrl]
 }

From 6d54013dd8c2ace1ea7560939638aa503e74a6de Mon Sep 17 00:00:00 2001
From: beyondkmp <beyondkmp@gmail.com>
Date: Wed, 18 Jun 2025 19:50:21 +0800
Subject: [PATCH 03/10] refactor(updater): encapsulate oldBlockMapFileBaseUrl
 with getter and setter

- Changed `oldBlockMapFileBaseUrl` to a private property and added public getter and setter methods for better encapsulation.
- Updated references in the `blockmapFiles` function to use the new private property.
- Cleaned up the logic for generating the old block map URL in the `blockmapFiles` function.
---
 packages/electron-updater/src/AppUpdater.ts          | 12 ++++++++++--
 .../multipleRangeDownloader.ts                       |  2 +-
 packages/electron-updater/src/util.ts                |  8 +-------
 3 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/packages/electron-updater/src/AppUpdater.ts b/packages/electron-updater/src/AppUpdater.ts
index 046943e31c7..2d1d46e10b9 100644
--- a/packages/electron-updater/src/AppUpdater.ts
+++ b/packages/electron-updater/src/AppUpdater.ts
@@ -121,7 +121,7 @@ export abstract class AppUpdater extends (EventEmitter as new () => TypedEmitter
    * The base URL of the old block map file.
    * @default null
    */
-  oldBlockMapFileBaseUrl: string | null = null
+  private _oldBlockMapFileBaseUrl: string | null = null
 
   /**
    * The current application version.
@@ -139,6 +139,14 @@ export abstract class AppUpdater extends (EventEmitter as new () => TypedEmitter
     return this._channel
   }
 
+  get oldBlockMapFileBaseUrl(): string | null {
+    return this._oldBlockMapFileBaseUrl
+  }
+
+  set oldBlockMapFileBaseUrl(value: string | null) {
+    this._oldBlockMapFileBaseUrl = value
+  }
+
   /**
    * Set the update channel. Overrides `channel` in the update configuration.
    *
@@ -796,7 +804,7 @@ export abstract class AppUpdater extends (EventEmitter as new () => TypedEmitter
       if (this._testOnlyOptions != null && !this._testOnlyOptions.isUseDifferentialDownload) {
         return true
       }
-      const blockmapFileUrls = blockmapFiles(fileInfo.url, this.app.version, downloadUpdateOptions.updateInfoAndProvider.info.version, this.oldBlockMapFileBaseUrl)
+      const blockmapFileUrls = blockmapFiles(fileInfo.url, this.app.version, downloadUpdateOptions.updateInfoAndProvider.info.version, this._oldBlockMapFileBaseUrl)
       this._logger.info(`Download block maps (old: "${blockmapFileUrls[0]}", new: ${blockmapFileUrls[1]})`)
 
       const downloadBlockMap = async (url: URL): Promise<BlockMap> => {
diff --git a/packages/electron-updater/src/differentialDownloader/multipleRangeDownloader.ts b/packages/electron-updater/src/differentialDownloader/multipleRangeDownloader.ts
index 7b29a2fc1a9..b7b36f074bb 100644
--- a/packages/electron-updater/src/differentialDownloader/multipleRangeDownloader.ts
+++ b/packages/electron-updater/src/differentialDownloader/multipleRangeDownloader.ts
@@ -46,7 +46,7 @@ function doExecuteTasks(differentialDownloader: DifferentialDownloader, options:
   for (let i = options.start; i < options.end; i++) {
     const task = options.tasks[i]
     if (task.kind === OperationKind.DOWNLOAD) {
-      ranges += `${task.start}-${task.end - 1}, `
+      ranges += `${task.start}-${task.end - 1},`
       partIndexToTaskIndex.set(partCount, i)
       partCount++
       partIndexToLength.push(task.end - task.start)
diff --git a/packages/electron-updater/src/util.ts b/packages/electron-updater/src/util.ts
index 571cb59723d..3c4da9505a2 100644
--- a/packages/electron-updater/src/util.ts
+++ b/packages/electron-updater/src/util.ts
@@ -32,13 +32,7 @@ export function getChannelFilename(channel: string): string {
 
 export function blockmapFiles(baseUrl: URL, oldVersion: string, newVersion: string, oldBlockMapFileBaseUrl: string | null = null): URL[] {
   const newBlockMapUrl = newUrlFromBase(`${baseUrl.pathname}.blockmap`, baseUrl)
-
-  let oldBlockMapUrl: URL | null = null
-  if (oldBlockMapFileBaseUrl) {
-    oldBlockMapUrl = new URL(`${oldBlockMapFileBaseUrl}.blockmap`)
-  } else {
-    oldBlockMapUrl = newUrlFromBase(`${baseUrl.pathname.replace(new RegExp(escapeRegExp(newVersion), "g"), oldVersion)}.blockmap`, baseUrl)
-  }
+  const oldBlockMapUrl = newUrlFromBase(`${baseUrl.pathname.replace(new RegExp(escapeRegExp(newVersion), "g"), oldVersion)}.blockmap`, oldBlockMapFileBaseUrl ? new URL(oldBlockMapFileBaseUrl) : baseUrl)
 
   return [oldBlockMapUrl, newBlockMapUrl]
 }

From c4add6bade9b07221f4396ca2026e89113ac7849 Mon Sep 17 00:00:00 2001
From: beyondkmp <beyondkmp@gmail.com>
Date: Thu, 19 Jun 2025 09:14:01 +0800
Subject: [PATCH 04/10] cache the new old blockmap

---
 packages/electron-updater/src/AppUpdater.ts | 37 ++++++++++++++++++---
 packages/electron-updater/src/util.ts       |  5 ++-
 2 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/packages/electron-updater/src/AppUpdater.ts b/packages/electron-updater/src/AppUpdater.ts
index 2d1d46e10b9..002c74eae2f 100644
--- a/packages/electron-updater/src/AppUpdater.ts
+++ b/packages/electron-updater/src/AppUpdater.ts
@@ -15,7 +15,7 @@ import {
 import { randomBytes } from "crypto"
 import { release } from "os"
 import { EventEmitter } from "events"
-import { mkdir, outputFile, readFile, rename, unlink } from "fs-extra"
+import { mkdir, outputFile, readFile, rename, unlink, copyFile, pathExists } from "fs-extra"
 import { OutgoingHttpHeaders } from "http"
 import { load } from "js-yaml"
 import { Lazy } from "lazy-val"
@@ -31,7 +31,7 @@ import { Provider, ProviderPlatform } from "./providers/Provider"
 import type { TypedEmitter } from "tiny-typed-emitter"
 import Session = Electron.Session
 import type { AuthInfo } from "electron"
-import { gunzipSync } from "zlib"
+import { gunzipSync, gzipSync } from "zlib"
 import { blockmapFiles } from "./util"
 import { DifferentialDownloaderOptions } from "./differentialDownloader/DifferentialDownloader"
 import { GenericDifferentialDownloader } from "./differentialDownloader/GenericDifferentialDownloader"
@@ -750,6 +750,10 @@ export abstract class AppUpdater extends (EventEmitter as new () => TypedEmitter
         ...updateInfo,
         downloadedFile: updateFile,
       })
+      const currentBlockMapFile = path.join(cacheDir, "current.blockmap")
+      if (await pathExists(currentBlockMapFile)) {
+        await copyFile(currentBlockMapFile, path.join(downloadedUpdateHelper.cacheDir, "current.blockmap"))
+      }
       return packageFile == null ? [updateFile] : [updateFile, packageFile]
     }
 
@@ -838,8 +842,33 @@ export abstract class AppUpdater extends (EventEmitter as new () => TypedEmitter
         downloadOptions.onProgress = it => this.emit(DOWNLOAD_PROGRESS, it)
       }
 
-      const blockMapDataList = await Promise.all(blockmapFileUrls.map(u => downloadBlockMap(u)))
-      await new GenericDifferentialDownloader(fileInfo.info, this.httpExecutor, downloadOptions).download(blockMapDataList[0], blockMapDataList[1])
+      const saveBlockMapToCacheDir = async (blockMapData: BlockMap, cacheDir: string) => {
+        const blockMapFile = path.join(cacheDir, "current.blockmap")
+        await outputFile(blockMapFile, gzipSync(JSON.stringify(blockMapData)))
+      }
+
+      const getBlockMapFromCacheDir = async (cacheDir: string) => {
+        const blockMapFile = path.join(cacheDir, "current.blockmap")
+        try {
+          if (await pathExists(blockMapFile)) {
+            return JSON.parse(gunzipSync(await readFile(blockMapFile)).toString())
+          }
+        } catch (e: any) {
+          this._logger.warn(`Cannot parse blockmap "${blockMapFile}", error: ${e}`)
+        }
+        return null
+      }
+
+      const newBlockMapData = await downloadBlockMap(blockmapFileUrls[0])
+      await saveBlockMapToCacheDir(newBlockMapData, this.downloadedUpdateHelper!.cacheDirForPendingUpdate)
+
+      // get old blockmap from cache dir first, if not found, download it
+      let oldBlockMapData = await getBlockMapFromCacheDir(this.downloadedUpdateHelper!.cacheDir)
+      if (oldBlockMapData == null) {
+        oldBlockMapData = await downloadBlockMap(blockmapFileUrls[1])
+      }
+
+      await new GenericDifferentialDownloader(fileInfo.info, this.httpExecutor, downloadOptions).download(newBlockMapData, oldBlockMapData)
       return false
     } catch (e: any) {
       this._logger.error(`Cannot download differentially, fallback to full download: ${e.stack || e}`)
diff --git a/packages/electron-updater/src/util.ts b/packages/electron-updater/src/util.ts
index 3c4da9505a2..e9f0d652ff1 100644
--- a/packages/electron-updater/src/util.ts
+++ b/packages/electron-updater/src/util.ts
@@ -32,7 +32,10 @@ export function getChannelFilename(channel: string): string {
 
 export function blockmapFiles(baseUrl: URL, oldVersion: string, newVersion: string, oldBlockMapFileBaseUrl: string | null = null): URL[] {
   const newBlockMapUrl = newUrlFromBase(`${baseUrl.pathname}.blockmap`, baseUrl)
-  const oldBlockMapUrl = newUrlFromBase(`${baseUrl.pathname.replace(new RegExp(escapeRegExp(newVersion), "g"), oldVersion)}.blockmap`, oldBlockMapFileBaseUrl ? new URL(oldBlockMapFileBaseUrl) : baseUrl)
+  const oldBlockMapUrl = newUrlFromBase(
+    `${baseUrl.pathname.replace(new RegExp(escapeRegExp(newVersion), "g"), oldVersion)}.blockmap`,
+    oldBlockMapFileBaseUrl ? new URL(oldBlockMapFileBaseUrl) : baseUrl
+  )
 
   return [oldBlockMapUrl, newBlockMapUrl]
 }

From fa3b24f27c203dcbd09c96ae6d0f9d17eddd2d75 Mon Sep 17 00:00:00 2001
From: beyondkmp <beyondkmp@gmail.com>
Date: Thu, 19 Jun 2025 09:20:56 +0800
Subject: [PATCH 05/10] fix order

---
 packages/electron-updater/src/AppUpdater.ts | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/packages/electron-updater/src/AppUpdater.ts b/packages/electron-updater/src/AppUpdater.ts
index 002c74eae2f..0181cfdfd4f 100644
--- a/packages/electron-updater/src/AppUpdater.ts
+++ b/packages/electron-updater/src/AppUpdater.ts
@@ -859,16 +859,16 @@ export abstract class AppUpdater extends (EventEmitter as new () => TypedEmitter
         return null
       }
 
-      const newBlockMapData = await downloadBlockMap(blockmapFileUrls[0])
+      const newBlockMapData = await downloadBlockMap(blockmapFileUrls[1])
       await saveBlockMapToCacheDir(newBlockMapData, this.downloadedUpdateHelper!.cacheDirForPendingUpdate)
 
       // get old blockmap from cache dir first, if not found, download it
       let oldBlockMapData = await getBlockMapFromCacheDir(this.downloadedUpdateHelper!.cacheDir)
       if (oldBlockMapData == null) {
-        oldBlockMapData = await downloadBlockMap(blockmapFileUrls[1])
+        oldBlockMapData = await downloadBlockMap(blockmapFileUrls[0])
       }
 
-      await new GenericDifferentialDownloader(fileInfo.info, this.httpExecutor, downloadOptions).download(newBlockMapData, oldBlockMapData)
+      await new GenericDifferentialDownloader(fileInfo.info, this.httpExecutor, downloadOptions).download(oldBlockMapData, newBlockMapData)
       return false
     } catch (e: any) {
       this._logger.error(`Cannot download differentially, fallback to full download: ${e.stack || e}`)

From 27f9c615eed31c4d0f982a1f2071975b7f164002 Mon Sep 17 00:00:00 2001
From: beyondkmp <beyondkmp@gmail.com>
Date: Thu, 19 Jun 2025 09:28:04 +0800
Subject: [PATCH 06/10] format code

---
 test/src/binDownloadTest.ts | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/test/src/binDownloadTest.ts b/test/src/binDownloadTest.ts
index 327017d18e3..3ed5706c5c7 100644
--- a/test/src/binDownloadTest.ts
+++ b/test/src/binDownloadTest.ts
@@ -17,7 +17,7 @@ test("download binary from Mirror with custom dir", async ({ expect }) => {
     "linux-tools-mac-10.12.3.7z",
     "SQ8fqIRVXuQVWnVgaMTDWyf2TLAJjJYw3tRSqQJECmgF6qdM7Kogfa6KD49RbGzzMYIFca9Uw3MdsxzOPRWcYw=="
   )
-    delete process.env.ELECTRON_BUILDER_BINARIES_MIRROR
+  delete process.env.ELECTRON_BUILDER_BINARIES_MIRROR
   delete process.env.ELECTRON_BUILDER_BINARIES_CUSTOM_DIR
   expect(bin).toBeTruthy()
 })
@@ -29,7 +29,7 @@ test("download binary from Mirror", async ({ expect }) => {
     "linux-tools-mac-10.12.3.7z",
     "SQ8fqIRVXuQVWnVgaMTDWyf2TLAJjJYw3tRSqQJECmgF6qdM7Kogfa6KD49RbGzzMYIFca9Uw3MdsxzOPRWcYw=="
   )
-    delete process.env.ELECTRON_BUILDER_BINARIES_MIRROR
+  delete process.env.ELECTRON_BUILDER_BINARIES_MIRROR
   expect(bin).toBeTruthy()
 })
 
@@ -40,6 +40,6 @@ test("download binary from Mirror with Url override", async ({ expect }) => {
     "linux-tools-mac-10.12.3.7z",
     "SQ8fqIRVXuQVWnVgaMTDWyf2TLAJjJYw3tRSqQJECmgF6qdM7Kogfa6KD49RbGzzMYIFca9Uw3MdsxzOPRWcYw=="
   )
-    delete process.env.ELECTRON_BUILDER_BINARIES_DOWNLOAD_OVERRIDE_URL
+  delete process.env.ELECTRON_BUILDER_BINARIES_DOWNLOAD_OVERRIDE_URL
   expect(bin).toBeTruthy()
 })

From 30071a6b075e8e4f60fddf57576bba25edbe9d44 Mon Sep 17 00:00:00 2001
From: beyondkmp <beyondkmp@gmail.com>
Date: Fri, 20 Jun 2025 19:35:50 +0800
Subject: [PATCH 07/10] docs(updater): enhance documentation for
 oldBlockMapFileBaseUrl property

- Added detailed comments explaining the behavior of the oldBlockMapFileBaseUrl property in the AppUpdater class.
- Clarified the conditions under which the updater uses the base URL for the old block map file.
---
 packages/electron-updater/src/AppUpdater.ts                 | 6 ++++++
 .../src/differentialDownloader/multipleRangeDownloader.ts   | 2 +-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/packages/electron-updater/src/AppUpdater.ts b/packages/electron-updater/src/AppUpdater.ts
index 0181cfdfd4f..e5317b04e9d 100644
--- a/packages/electron-updater/src/AppUpdater.ts
+++ b/packages/electron-updater/src/AppUpdater.ts
@@ -119,6 +119,12 @@ export abstract class AppUpdater extends (EventEmitter as new () => TypedEmitter
 
   /**
    * The base URL of the old block map file.
+   *
+   * When null, the updater will use the base URL of the update file to download the update.
+   * When set, the updater will use this string as the base URL of the old block map file.
+   * Some servers like github cannot download the old block map file from latest release,
+   * so you need to compute the old block map file base URL manually.
+   *
    * @default null
    */
   private _oldBlockMapFileBaseUrl: string | null = null
diff --git a/packages/electron-updater/src/differentialDownloader/multipleRangeDownloader.ts b/packages/electron-updater/src/differentialDownloader/multipleRangeDownloader.ts
index b7b36f074bb..7b29a2fc1a9 100644
--- a/packages/electron-updater/src/differentialDownloader/multipleRangeDownloader.ts
+++ b/packages/electron-updater/src/differentialDownloader/multipleRangeDownloader.ts
@@ -46,7 +46,7 @@ function doExecuteTasks(differentialDownloader: DifferentialDownloader, options:
   for (let i = options.start; i < options.end; i++) {
     const task = options.tasks[i]
     if (task.kind === OperationKind.DOWNLOAD) {
-      ranges += `${task.start}-${task.end - 1},`
+      ranges += `${task.start}-${task.end - 1}, `
       partIndexToTaskIndex.set(partCount, i)
       partCount++
       partIndexToLength.push(task.end - task.start)

From a117225306db6454a992e97e4e96355d62aee07f Mon Sep 17 00:00:00 2001
From: beyondkmp <beyondkmp@gmail.com>
Date: Fri, 20 Jun 2025 19:37:57 +0800
Subject: [PATCH 08/10] add changeset

---
 .changeset/orange-experts-do.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/orange-experts-do.md

diff --git a/.changeset/orange-experts-do.md b/.changeset/orange-experts-do.md
new file mode 100644
index 00000000000..d7559489ab2
--- /dev/null
+++ b/.changeset/orange-experts-do.md
@@ -0,0 +1,5 @@
+---
+"electron-updater": patch
+---
+
+feat(updater): Cache the new blockmap file and allow customization of the old blockmap file base URL

From 35eb8c933a306fadd25f216618039b196734249b Mon Sep 17 00:00:00 2001
From: beyondkmp <beyondkmp@gmail.com>
Date: Sat, 21 Jun 2025 08:10:50 +0800
Subject: [PATCH 09/10] refactor(updater): replace oldBlockMapFileBaseUrl with
 previousBlockmapBaseUrlOverride

- Renamed the property `oldBlockMapFileBaseUrl` to `previousBlockmapBaseUrlOverride` for clarity.
- Removed the getter and setter methods associated with the old property to simplify the code structure.
---
 packages/electron-updater/src/AppUpdater.ts | 10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

diff --git a/packages/electron-updater/src/AppUpdater.ts b/packages/electron-updater/src/AppUpdater.ts
index e5317b04e9d..893d4dd1489 100644
--- a/packages/electron-updater/src/AppUpdater.ts
+++ b/packages/electron-updater/src/AppUpdater.ts
@@ -127,7 +127,7 @@ export abstract class AppUpdater extends (EventEmitter as new () => TypedEmitter
    *
    * @default null
    */
-  private _oldBlockMapFileBaseUrl: string | null = null
+  public previousBlockmapBaseUrlOverride: string | null = null
 
   /**
    * The current application version.
@@ -145,14 +145,6 @@ export abstract class AppUpdater extends (EventEmitter as new () => TypedEmitter
     return this._channel
   }
 
-  get oldBlockMapFileBaseUrl(): string | null {
-    return this._oldBlockMapFileBaseUrl
-  }
-
-  set oldBlockMapFileBaseUrl(value: string | null) {
-    this._oldBlockMapFileBaseUrl = value
-  }
-
   /**
    * Set the update channel. Overrides `channel` in the update configuration.
    *

From 9d0b8a3b055e024065eddfee60bfc92a4a553035 Mon Sep 17 00:00:00 2001
From: beyondkmp <beyondkmp@gmail.com>
Date: Sat, 21 Jun 2025 08:21:27 +0800
Subject: [PATCH 10/10] fix(updater): update blockmap file URL reference to use
 previousBlockmapBaseUrlOverride

- Changed the reference in the blockmapFiles function to use the new property `previousBlockmapBaseUrlOverride` instead of the deprecated `oldBlockMapFileBaseUrl`.
---
 packages/electron-updater/src/AppUpdater.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/electron-updater/src/AppUpdater.ts b/packages/electron-updater/src/AppUpdater.ts
index 893d4dd1489..53d9053ed71 100644
--- a/packages/electron-updater/src/AppUpdater.ts
+++ b/packages/electron-updater/src/AppUpdater.ts
@@ -806,7 +806,7 @@ export abstract class AppUpdater extends (EventEmitter as new () => TypedEmitter
       if (this._testOnlyOptions != null && !this._testOnlyOptions.isUseDifferentialDownload) {
         return true
       }
-      const blockmapFileUrls = blockmapFiles(fileInfo.url, this.app.version, downloadUpdateOptions.updateInfoAndProvider.info.version, this._oldBlockMapFileBaseUrl)
+      const blockmapFileUrls = blockmapFiles(fileInfo.url, this.app.version, downloadUpdateOptions.updateInfoAndProvider.info.version, this.previousBlockmapBaseUrlOverride)
       this._logger.info(`Download block maps (old: "${blockmapFileUrls[0]}", new: ${blockmapFileUrls[1]})`)
 
       const downloadBlockMap = async (url: URL): Promise<BlockMap> => {