diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index a1d1aa2..e031850 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -148,6 +148,8 @@ jobs:
           Get-ChildItem converter/*.dll | ForEach-Object { Write-Output "Bundled $($_.Name) ($($_.Length) bytes)" }
 
       - name: Build allfontsgen
+        env:
+          ALLFONTSGEN_FORCE_REBUILD: ${{ runner.os == 'Windows' && '1' || '0' }}
         run: bun scripts/build_allfontsgen.js
 
       - name: Install production dependencies
diff --git a/scripts/build_allfontsgen.js b/scripts/build_allfontsgen.js
index c49859f..3b6cdb4 100755
--- a/scripts/build_allfontsgen.js
+++ b/scripts/build_allfontsgen.js
@@ -25,12 +25,24 @@ const CORE_REPO = 'https://github.com/ONLYOFFICE/core.git';
 const CORE_COMMIT = '82e281cf6bf89498e4de6018423b36576706c2b6';
 const SRC = path.join(CORE_DIR, 'DesktopEditor', 'AllFontsGen', 'main.cpp');
 const WINDOWS_COMPONENTS = ['graphics', 'kernel', 'UnicodeConverter'];
+const FORCE_ALLFONTSGEN_REBUILD = process.env.ALLFONTSGEN_FORCE_REBUILD === '1';
+const ALLFONTSGEN_DIAGNOSTICS_PATCH = path.join(
+  ROOT,
+  'scripts',
+  'patches',
+  'allfontsgen-control-diagnostics.patch'
+);
 let cachedConverterArch = null;
 
 const platform = process.platform; // 'darwin', 'win32', 'linux'
 
 // Early return if allfontsgen binary already exists
 function checkExistingBinary() {
+  if (FORCE_ALLFONTSGEN_REBUILD) {
+    console.log('[build_allfontsgen] ALLFONTSGEN_FORCE_REBUILD=1, rebuilding binary');
+    return false;
+  }
+
   if (platform === 'darwin') {
     const output = path.join(CONVERTER_DIR, 'allfontsgen');
     if (fs.existsSync(output)) {
@@ -364,12 +376,25 @@ function ensureCoreSources() {
 
   console.log(`[build_allfontsgen] Checking out ONLYOFFICE/core commit ${CORE_COMMIT}...`);
   run('git', ['fetch', '--all'], { cwd: CORE_DIR });
-  run('git', ['checkout', CORE_COMMIT], { cwd: CORE_DIR });
+  run('git', ['checkout', '--force', CORE_COMMIT], { cwd: CORE_DIR });
   console.log('[build_allfontsgen] Updating ONLYOFFICE/core submodules...');
   run('git', ['submodule', 'update', '--init', '--recursive', '--force'], { cwd: CORE_DIR });
 }
 
+function applyAllFontsGenDiagnosticsPatch() {
+  if (!fs.existsSync(ALLFONTSGEN_DIAGNOSTICS_PATCH)) {
+    console.error('[build_allfontsgen] Missing diagnostics patch:', ALLFONTSGEN_DIAGNOSTICS_PATCH);
+    process.exit(1);
+  }
+
+  console.log('[build_allfontsgen] Applying AllFontsGen diagnostics patch...');
+  run('git', ['apply', '--unidiff-zero', '--whitespace=nowarn', ALLFONTSGEN_DIAGNOSTICS_PATCH], {
+    cwd: CORE_DIR,
+  });
+}
+
 ensureCoreSources();
+applyAllFontsGenDiagnosticsPatch();
 
 if (!fs.existsSync(SRC)) {
   console.error('[build_allfontsgen] main.cpp not found:', SRC);
diff --git a/scripts/generate_office_fonts.js b/scripts/generate_office_fonts.js
index 7d2fec5..6e6c714 100755
--- a/scripts/generate_office_fonts.js
+++ b/scripts/generate_office_fonts.js
@@ -63,6 +63,7 @@ function locateBinary() {
 const BIN = locateBinary();
 
 const INPUT_DIR = path.join(OUTPUT_DIR, 'fonts');
+const DIAG_LOG = path.join(OUTPUT_DIR, 'allfontsgen-control.log');
 
 fs.mkdirSync(OUTPUT_DIR, { recursive: true });
 fs.mkdirSync(INPUT_DIR, { recursive: true });
@@ -78,18 +79,56 @@ const env = { ...process.env };
 if (platform === 'darwin') {
   env.DYLD_FRAMEWORK_PATH = CONVERTER_DIR;
 }
+if (platform === 'win32') {
+  env.ALLFONTSGEN_DIAG_LOG = DIAG_LOG;
+}
+
+function readDiagnosticLog() {
+  if (platform !== 'win32' || !fs.existsSync(DIAG_LOG)) {
+    return '';
+  }
+
+  const text = fs.readFileSync(DIAG_LOG, 'utf8').trim();
+  if (!text) {
+    return '';
+  }
+
+  const normalizedText = text.replaceAll('\r\n', '\n');
+  return `\n[generate_office_fonts] allfontsgen diagnostic log:\n${normalizedText}`;
+}
+
+function formatExitStatus(status) {
+  if (typeof status !== 'number') {
+    return String(status);
+  }
+
+  return `${status} (0x${(status >>> 0).toString(16).toUpperCase()})`;
+}
 
 const result = spawnSync(BIN, args, { stdio: 'inherit', env });
 
 if (result.status !== 0) {
-  fail(`allfontsgen exited with code ${result.status || 1}`);
+  const details = [
+    `allfontsgen exited with code ${formatExitStatus(result.status)}`,
+    result.signal ? `signal=${result.signal}` : null,
+    result.error ? `error=${result.error.message}` : null,
+  ].filter(Boolean).join(' ');
+
+  fail(`${details}${readDiagnosticLog()}`);
 }
 
 const allFontsJs = path.join(OUTPUT_DIR, 'AllFonts.js');
 const fontSelectionBin = path.join(OUTPUT_DIR, 'font_selection.bin');
 
 if (!fs.existsSync(allFontsJs) || !fs.existsSync(fontSelectionBin)) {
-  fail('allfontsgen exited successfully but font metadata files were not created');
+  const missing = [
+    fs.existsSync(allFontsJs) ? null : allFontsJs,
+    fs.existsSync(fontSelectionBin) ? null : fontSelectionBin,
+  ].filter(Boolean);
+
+  fail(
+    `allfontsgen exited successfully but font metadata files were not created; missing=${missing.join(', ')}${readDiagnosticLog()}`
+  );
 }
 
 console.log('[generate_office_fonts] Font metadata updated.');
diff --git a/scripts/patches/allfontsgen-control-diagnostics.patch b/scripts/patches/allfontsgen-control-diagnostics.patch
new file mode 100644
index 0000000..2fd0b35
--- /dev/null
+++ b/scripts/patches/allfontsgen-control-diagnostics.patch
@@ -0,0 +1,65 @@
+diff --git a/DesktopEditor/AllFontsGen/main.cpp b/DesktopEditor/AllFontsGen/main.cpp
+--- a/DesktopEditor/AllFontsGen/main.cpp
++++ b/DesktopEditor/AllFontsGen/main.cpp
+@@ -33,0 +34,2 @@
++#include <fstream>
++#include <cstdlib>
+@@ -42,0 +45,49 @@
++
++#ifdef _WIN32
++#include <windows.h>
++
++static std::wstring g_allFontsGenDiagLogPath;
++static std::wstring g_allFontsGenOutputDir;
++
++static void AppendAllFontsGenDiagLine(const wchar_t* stage, DWORD eventType = MAXDWORD)
++{
++	if (g_allFontsGenDiagLogPath.empty())
++		return;
++
++	std::wofstream file(g_allFontsGenDiagLogPath.c_str(), std::ios::app);
++	if (!file.is_open())
++		return;
++
++	SYSTEMTIME now;
++	GetSystemTime(&now);
++	file << L"utc="
++	     << now.wYear << L"-" << now.wMonth << L"-" << now.wDay
++	     << L"T" << now.wHour << L":" << now.wMinute << L":" << now.wSecond
++	     << L"." << now.wMilliseconds << L"Z"
++	     << L" stage=" << stage
++	     << L" pid=" << GetCurrentProcessId();
++
++	if (eventType != MAXDWORD)
++		file << L" eventCode=" << eventType;
++
++	file << L" outputDir=\"" << g_allFontsGenOutputDir << L"\"" << std::endl;
++}
++
++static BOOL WINAPI AllFontsGenConsoleCtrlHandler(DWORD eventType)
++{
++	AppendAllFontsGenDiagLine(L"console-control", eventType);
++	return FALSE;
++}
++
++static void InitAllFontsGenDiagnostics(const std::wstring& outputDir)
++{
++	const wchar_t* logPath = _wgetenv(L"ALLFONTSGEN_DIAG_LOG");
++	if (!logPath || !logPath[0])
++		return;
++
++	g_allFontsGenDiagLogPath = logPath;
++	g_allFontsGenOutputDir = outputDir;
++	SetConsoleCtrlHandler(AllFontsGenConsoleCtrlHandler, TRUE);
++	AppendAllFontsGenDiagLine(L"start");
++}
++#endif
+@@ -209,0 +261,4 @@
++#ifdef _WIN32
++	InitAllFontsGenDiagnostics(oWorker.m_sDirectory);
++#endif
++
+@@ -225,0 +281,3 @@
++#ifdef _WIN32
++	AppendAllFontsGenDiagLine(pApplicationFonts ? L"after-check-non-null" : L"after-check-null");
++#endif