Auto-install .NET 8 runtimes if missing

A fresh Windows Server install has neither ASP.NET Core 8 nor .NET
Desktop 8, so the Service refuses to start and the GUI fails to
launch — the symptoms link to aka.ms/dotnet-core-applaunch but it's
not obvious from the GUI itself what's wrong.

Setup now:
- Detects each runtime by looking for an 8.x folder under
  %ProgramFiles%\dotnet\shared\Microsoft.{AspNetCore,WindowsDesktop}.App
- Uses Inno Setup's built-in TDownloadWizardPage to fetch any missing
  runtime from the aka.ms redirect and runs `/install /quiet /norestart`
- Treats Microsoft's 1638 / 3010 / 1641 exit codes as success

If the box has no internet, the prereq install fails with a clear
message and a "continue anyway?" prompt. README + installation docs
list the manual download URLs and `dotnet --list-runtimes` check;
troubleshooting has a section pointing at the same fix when the
service won't start after install.

README.md

@@ -7,7 +7,7 @@ Designed for sysadmins who want to wire up tools like **Zerto pre/post scripts**
 ## Quickstart
 
 1. **Download** the latest installer: <https://github.com/recklessop/webhook-server/releases/latest>
-2. **Run it.** UAC accept → next, next, finish. Adds a Start Menu entry, registers and starts the Windows Service.
+2. **Run it.** UAC accept → next, next, finish. Adds a Start Menu entry, registers and starts the Windows Service. The installer also downloads + installs the **.NET 8 runtimes** (ASP.NET Core + Desktop) if they're missing — fresh Windows Server installs need this.
 3. **Open Webhook Server** from the Start Menu (auto-elevates).
 4. **File → New endpoint**, configure a slug + script, save, hit the URL.
 

docs/installation.md

@@ -6,10 +6,34 @@ This page covers a fresh install. If you already have Webhook Server installed,
 
 - Windows 10, Windows 11, or Windows Server 2019 / 2022 / 2025
 - Administrator rights to install the service and to run the GUI
+- **.NET 8 runtimes** (the installer downloads + installs them automatically if missing — see below)
 - (Optional, only if you publish from source) .NET 8 SDK
 
 The installer is **x64 only**. There is no x86 build.
 
+### .NET 8 runtimes
+
+Webhook Server is published as framework-dependent (so the installer stays small) and needs two .NET 8 runtimes on the target machine:
+
+| Runtime | Used by | Auto-installed by setup |
+|---|---|---|
+| ASP.NET Core 8 Runtime (`Microsoft.AspNetCore.App` 8.x) | the Service / Kestrel | Yes |
+| .NET Desktop Runtime 8 (`Microsoft.WindowsDesktop.App` 8.x) | the WPF GUI | Yes |
+
+A clean Windows Server install has neither. The installer detects what's missing and downloads + installs each one silently before copying our files. If the machine has no internet access, install them manually first:
+
+- ASP.NET Core 8 Runtime — <https://aka.ms/dotnet/8.0/aspnetcore-runtime-win-x64.exe>
+- .NET Desktop Runtime 8 — <https://aka.ms/dotnet/8.0/windowsdesktop-runtime-win-x64.exe>
+
+Run each with `/install /quiet /norestart` for unattended installs, or just double-click. A reboot is rarely required.
+
+To check what's already installed:
+
+```powershell
+dotnet --list-runtimes
+# expect to see Microsoft.AspNetCore.App 8.x.y and Microsoft.WindowsDesktop.App 8.x.y
+```
+
 ## 1. Download
 
 Grab the latest installer from the GitHub Releases page:

docs/troubleshooting.md

@@ -38,6 +38,28 @@ You launched the GUI without elevation. The admin pipe ACL is `SYSTEM` + `Admini
 
 **Fix in v0.1.0**: right-click the Start Menu shortcut → **Run as administrator**, or upgrade.
 
+### Service won't start after install / GUI says "Disconnected" with no obvious error
+
+If `Get-Service WebhookServer` shows it stopped and `Start-Service WebhookServer` fails, or the GUI itself won't even launch, you're probably missing a .NET 8 runtime. The v0.1.4+ installer auto-fetches them, but a clean Windows Server box might still hit this if the install was offline or used an older installer.
+
+Check what's installed:
+
+```powershell
+dotnet --list-runtimes
+```
+
+You need both:
+
+- `Microsoft.AspNetCore.App 8.x.y` — for the Service
+- `Microsoft.WindowsDesktop.App 8.x.y` — for the GUI
+
+If either is missing, install from:
+
+- ASP.NET Core 8 Runtime — <https://aka.ms/dotnet/8.0/aspnetcore-runtime-win-x64.exe>
+- .NET Desktop Runtime 8 — <https://aka.ms/dotnet/8.0/windowsdesktop-runtime-win-x64.exe>
+
+Re-run with `/install /quiet /norestart` for unattended installs. Then `Start-Service WebhookServer`.
+
 ### "Connection refused" hitting the hook URL
 
 Three possibilities, in order of probability:

installer/webhook-server.iss

@@ -86,6 +86,17 @@ Filename: "powershell.exe"; \
     RunOnceId: "RemoveWebhookService"
 
 [Code]
+const
+  // aka.ms redirects to the latest 8.0.x patch. Inno Setup's downloader
+  // follows redirects via the Windows HTTP stack.
+  AspNetCore8Url  = 'https://aka.ms/dotnet/8.0/aspnetcore-runtime-win-x64.exe';
+  WinDesktop8Url  = 'https://aka.ms/dotnet/8.0/windowsdesktop-runtime-win-x64.exe';
+  AspNetCore8File = 'aspnetcore-runtime-8.0-win-x64.exe';
+  WinDesktop8File = 'windowsdesktop-runtime-8.0-win-x64.exe';
+
+var
+  DownloadPage: TDownloadWizardPage;
+
 function ServiceExists(): Boolean;
 var
   ResultCode: Integer;
@@ -96,6 +107,119 @@ begin
   Result := (ResultCode = 0);
 end;
 
+// True if a Microsoft.* shared-framework directory under
+// %ProgramFiles%\dotnet\shared contains at least one 8.x.y subfolder.
+function HasDotNet8(const RuntimeName: String): Boolean;
+var
+  rec: TFindRec;
+  base: String;
+begin
+  Result := False;
+  base := ExpandConstant('{commonpf}\dotnet\shared\') + RuntimeName;
+  if not DirExists(base) then Exit;
+  if FindFirst(base + '\8.*', rec) then
+  try
+    repeat
+      if (rec.Name <> '.') and (rec.Name <> '..') and
+         DirExists(base + '\' + rec.Name) then begin
+        Result := True;
+        Exit;
+      end;
+    until not FindNext(rec);
+  finally
+    FindClose(rec);
+  end;
+end;
+
+function NeedsAspNet8(): Boolean;
+begin
+  Result := not HasDotNet8('Microsoft.AspNetCore.App');
+end;
+
+function NeedsWinDesktop8(): Boolean;
+begin
+  Result := not HasDotNet8('Microsoft.WindowsDesktop.App');
+end;
+
+procedure InitializeWizard;
+begin
+  DownloadPage := CreateDownloadPage(
+    'Downloading prerequisites',
+    'Webhook Server needs the .NET 8 runtimes. Setup is fetching them now.',
+    nil);
+end;
+
+// Runs a downloaded runtime installer silently. Treats Microsoft's
+// "success but reboot pending" / "newer already installed" exit codes
+// as successes so we don't fail the whole install over a benign result.
+function RunRuntimeInstaller(const FileName, DisplayName: String): String;
+var
+  resultCode: Integer;
+  fullPath: String;
+begin
+  Result := '';
+  fullPath := ExpandConstant('{tmp}\') + FileName;
+  if not Exec(fullPath, '/install /quiet /norestart', '', SW_HIDE,
+              ewWaitUntilTerminated, resultCode) then begin
+    Result := 'Could not launch the ' + DisplayName + ' installer.';
+    Exit;
+  end;
+  case resultCode of
+    0, 1638, 3010, 1641: ;
+  else
+    Result := DisplayName + ' installer failed (exit code ' +
+              IntToStr(resultCode) + ').';
+  end;
+end;
+
+function NextButtonClick(CurPageID: Integer): Boolean;
+var
+  errMsg: String;
+begin
+  Result := True;
+  if CurPageID <> wpReady then Exit;
+  if not (NeedsAspNet8 or NeedsWinDesktop8) then Exit;
+
+  DownloadPage.Clear;
+  if NeedsAspNet8 then
+    DownloadPage.Add(AspNetCore8Url, AspNetCore8File, '');
+  if NeedsWinDesktop8 then
+    DownloadPage.Add(WinDesktop8Url, WinDesktop8File, '');
+  DownloadPage.Show;
+  try
+    try
+      DownloadPage.Download;
+    except
+      if MsgBox('Failed to download the .NET 8 runtimes:' + #13#10#13#10 +
+                GetExceptionMessage + #13#10#13#10 +
+                'Continue installing anyway? Webhook Server will not start ' +
+                'until the runtimes are installed manually.',
+                mbError, MB_YESNO) = IDNO then
+        Result := False;
+      Exit;
+    end;
+  finally
+    DownloadPage.Hide;
+  end;
+
+  if NeedsAspNet8 then begin
+    errMsg := RunRuntimeInstaller(AspNetCore8File, 'ASP.NET Core 8 Runtime');
+    if errMsg <> '' then begin
+      MsgBox(errMsg, mbError, MB_OK);
+      Result := False;
+      Exit;
+    end;
+  end;
+  if NeedsWinDesktop8 then begin
+    errMsg := RunRuntimeInstaller(WinDesktop8File, '.NET Desktop Runtime 8');
+    if errMsg <> '' then begin
+      MsgBox(errMsg, mbError, MB_OK);
+      Result := False;
+      Exit;
+    end;
+  end;
+end;
+
 function PrepareToInstall(var NeedsRestart: Boolean): String;
 var
   ResultCode: Integer;

scripts/build-installer.ps1

@@ -53,15 +53,125 @@ if ($LASTEXITCODE -ne 0) { throw 'service publish failed' }
     -c $Configuration -r win-x64 --self-contained false -o $publishGui | Out-Host
 if ($LASTEXITCODE -ne 0) { throw 'GUI publish failed' }
 
-# 2. Compile installer.
+# 2. Pre-flight: confirm every source path the .iss references exists, and
+#    surface the longest path so MAX_PATH issues are obvious in the log.
+function Show-SourcePath($label, $path, [switch]$Recursive) {
+    if (-not (Test-Path $path)) { Write-Warning "MISSING $label : $path"; return }
+    $items = if ($Recursive) {
+        Get-ChildItem $path -Recurse -File -ErrorAction SilentlyContinue
+    } else {
+        Get-ChildItem $path -File -ErrorAction SilentlyContinue
+    }
+    $count   = ($items | Measure-Object).Count
+    $longest = ($items | Measure-Object -Maximum -Property { $_.FullName.Length }).Maximum
+    Write-Host ("  {0,-30} files={1,-5} longestPath={2,-5} root={3}" -f $label, $count, $longest, $path)
+}
+
+Write-Host ""
+Write-Host "--- pre-flight: source paths the .iss will read ---" -ForegroundColor Cyan
+Show-SourcePath 'publish\service'        $publishSvc                              -Recursive
+Show-SourcePath 'publish\gui'            $publishGui                              -Recursive
+Show-SourcePath 'scripts'                (Join-Path $repoRoot 'scripts')
+Show-SourcePath 'scripts\examples'       (Join-Path $repoRoot 'scripts\examples') -Recursive
+Show-SourcePath 'docs'                   (Join-Path $repoRoot 'docs')             -Recursive
+Show-SourcePath 'resources'              (Join-Path $repoRoot 'resources')
+Show-SourcePath 'README.md (file)'       (Join-Path $repoRoot 'README.md')
+
+$lpe = (Get-ItemProperty 'HKLM:\SYSTEM\CurrentControlSet\Control\FileSystem' `
+            -Name LongPathsEnabled -ErrorAction SilentlyContinue).LongPathsEnabled
+Write-Host "  LongPathsEnabled (HKLM): $lpe"
+Write-Host ""
+
+# 3. Compile installer.
 $iscc = Find-InnoCompiler
 $iss = Join-Path $repoRoot 'installer\webhook-server.iss'
 $dist = Join-Path $repoRoot 'dist'
 New-Item -ItemType Directory -Path $dist -Force | Out-Null
 
 Write-Host "Compiling installer with $iscc"
-& $iscc "/DAppVersion=$version" $iss
-if ($LASTEXITCODE -ne 0) { throw 'Inno Setup compile failed' }
+# Run ISCC from the .iss directory with just the bare filename. When invoked
+# with a deeply-nested absolute path on the act-runner host (under
+# %SystemRoot%\System32\config\systemprofile\...), ISCC sometimes prints a
+# generic "The system cannot find the path specified." before it touches any
+# source files. cd-ing first sidesteps it.
+$issDir  = Split-Path $iss -Parent
+$issName = Split-Path $iss -Leaf
+
+# Extra pre-flight: confirm the specific files our .iss references that a
+# trivial test .iss wouldn't (icon, README, scripts) actually exist relative
+# to the .iss directory the way ISCC will resolve them (RepoRoot = ..\).
+Write-Host "--- pre-flight: paths the .iss references via {#RepoRoot} ---" -ForegroundColor Cyan
+$issRefs = @(
+    'resources\webhook-server.ico',
+    'README.md',
+    'scripts\install-service.ps1',
+    'scripts\uninstall-service.ps1',
+    'publish\service',
+    'publish\gui',
+    'docs',
+    'scripts\examples'
+)
+foreach ($ref in $issRefs) {
+    $abs = Join-Path $repoRoot $ref
+    $exists = Test-Path $abs
+    Write-Host ("  {0,-40} exists={1}  ({2})" -f $ref, $exists, $abs)
+}
+Write-Host ""
+
+Write-Host "--- runtime context ---" -ForegroundColor Cyan
+Write-Host "  whoami:        $(whoami)"
+Write-Host "  USERPROFILE:   $env:USERPROFILE"
+Write-Host "  APPDATA:       $env:APPDATA"
+Write-Host "  LOCALAPPDATA:  $env:LOCALAPPDATA"
+Write-Host "  TEMP:          $env:TEMP"
+$isccDir = Split-Path $iscc -Parent
+Write-Host "  ISCC dir:      $isccDir"
+foreach ($f in @('ISCC.exe','ISCmplr.dll','ISPP.dll','Default.isl','Compil32.exe')) {
+    $p = Join-Path $isccDir $f
+    Write-Host ("    {0,-15} exists={1}" -f $f, (Test-Path $p))
+}
+Write-Host ""
+
+Write-Host "  PS  location (pre):  $((Get-Location).Path)"
+Write-Host "  .NET cwd     (pre):  $([System.IO.Directory]::GetCurrentDirectory())"
+
+Push-Location $issDir
+$savedDotNetCwd = [System.IO.Directory]::GetCurrentDirectory()
+[System.IO.Directory]::SetCurrentDirectory($issDir)
+try {
+    Write-Host "  PS  location (post): $((Get-Location).Path)"
+    Write-Host "  .NET cwd     (post): $([System.IO.Directory]::GetCurrentDirectory())"
+
+    # Bake the version into a temp .iss and override OutputDir to an absolute
+    # path so nothing in the build depends on cwd resolution.
+    $tempIss = Join-Path $issDir "webhook-server.gen.iss"
+    $issBody = Get-Content $issName -Raw
+    $pattern = '(?s)#ifndef AppVersion\s+#define AppVersion "[^"]*"\s+#endif'
+    if ($issBody -notmatch $pattern) { throw "Could not find #ifndef AppVersion block in $issName" }
+    $issBody = $issBody -replace $pattern, "#define AppVersion `"$version`""
+    Set-Content -Path $tempIss -Value $issBody -Encoding ascii
+    Write-Host "  using $tempIss"
+
+    # Capture stdout+stderr together so any error line ISCC emits is visible
+    # in the runner log even if the runner's console capture drops one stream.
+    # /O<absolute> overrides OutputDir so ..\dist isn't resolved relative to
+    # whatever cwd ISCC actually inherits.
+    $logPath = Join-Path $env:TEMP "iscc-$version.log"
+    & $iscc "/O$dist" (Split-Path $tempIss -Leaf) *>&1 | Tee-Object -FilePath $logPath | ForEach-Object { Write-Host $_ }
+    $exit = $LASTEXITCODE
+    Write-Host "  ISCC exit code: $exit"
+    Write-Host "  ISCC log path:  $logPath"
+    if (Test-Path $logPath) {
+        Write-Host "  --- iscc log file contents ---"
+        Get-Content $logPath | ForEach-Object { Write-Host "    $_" }
+        Write-Host "  --- end iscc log ---"
+    }
+    Remove-Item $tempIss -ErrorAction SilentlyContinue
+} finally {
+    [System.IO.Directory]::SetCurrentDirectory($savedDotNetCwd)
+    Pop-Location
+}
+if ($exit -ne 0) { throw "Inno Setup compile failed (exit $exit)" }
 
 $out = Get-Item (Join-Path $dist "WebhookServer-Setup-$version.exe")
 Write-Host ""