How to find out which version of the .NET Framework an executable needs to run?

Using Notepad, three decades old, 200kb in size, preinstalled tool:

• open application with notepad appname.exe,
• search for word framework,
• repeat last search with F3 until .NET Framework,version=vX.Y shows up
• if nothing found (versions below 3.0) search for v2. ... still 100 times easier then installing gigabytes of dot net analyzer tools and garbage studios.

update: Thought and Marcus suggested in comments that search term could also be netstandard or netframework

I think the closest you can reliably get is to determine what version of the CLR is required. You can do this by using ILDASM and looking at the "MANIFEST" node or Reflector and looking at the dissasembly view of the "Application.exe" node as IL. In both cases there is a comment that indicates the CLR version. In ILDASM, the comment is "// Metadata version" and in Reflector the comment is "Target Runtime Version".

Here are examples for a .NET WinForms application named WindowsFormsApplication1.exe:

ILDASM:

// Metadata version: v2.0.50727
.assembly extern mscorlib
{
  .publickeytoken = (B7 7A 5C 56 19 34 E0 89 )                         // .z\V.4..
  .ver 2:0:0:0
}
.assembly extern System
{
  .publickeytoken = (B7 7A 5C 56 19 34 E0 89 )                         // .z\V.4..
  .ver 2:0:0:0
}

Reflector:

.module WindowsFormsApplication1.exe
.subsystem 0x0002
// MVID: {CA3D2090-16C5-4899-953E-4736D6BC0FA8}
// Target Runtime Version: v2.0.50727

You can also look at the list of referenced assemblies and look for the reference with the highest version number.

Again, using ILDASM looking at the "MANIFEST" node data:

.assembly extern System.Drawing
{
  .publickeytoken = (B0 3F 5F 7F 11 D5 0A 3A )                         // .?_....:
  .ver 2:0:0:0
}
.assembly extern System.Core
{
  .publickeytoken = (B7 7A 5C 56 19 34 E0 89 )                         // .z\V.4..
  .ver 3:5:0:0
}

And using Reflector, looking at the dissambly (still as IL) for each reference listed:

.assembly extern System.Core
{
    .ver 3:5:0:0
    .publickeytoken = (B7 7A 5C 56 19 34 E0 89)
}

By finding the reference with the highest version metadata you can determine what version of the Framework that reference came from, which would indicate that you need the same version of the Framework installed for the application to run. That being said, I wouldn't treat this as 100% reliable, but I don't think it will change any time soon.

You can use a tool called CorFlags.exe. It has been around since .NET 2.0, and I know for sure that it is included in the Windows SDK 7.0. By default (on Windows XP Pro) it is installed to C:\Program Files\Microsoft SDKs\Windows\v7.0A\bin\CorFlags.exe. Provide it with the file path to a managed module (without any other command-line flags) to display its header information, which includes the version.

Keep in mind that this utility is designed to modify the PE32 header of a module, so don't use any of the flags until you read the documentation carefully.

You can obtain the .NET version of a file in Windows using Powershell. The following script;

$path=’.\’
$ErrorActionPreference = "SilentlyContinue"
$files=Get-ChildItem -Path $path -Recurse -include *.dll,*.exe
foreach($file in $files)
{
    $filename = $file.BaseName
    $version = $([System.Reflection.Assembly]::ReflectionOnlyLoadFrom($file.FullName).GetCustomAttributesData() |
                 select-object -ExpandProperty ConstructorArguments | 
                 select-object -ExpandProperty Value | 
                 select-string -Pattern '.NET')
    Write-Output "$filename,$version"
}

provides the following result;

Note that the result extracted the .NET version for the exe files in that folder, but it will also do the same for a dll.

On Linux/OSX/unix you can use:

strings that_app.exe | grep 'v2.\|Framework'

For newer .NET 6.0 applications the notepad method did not work for me, but if there is a *.deps.json file next to the exes that's a big clue - often contains the version in form of the following section

"runtimeTarget": {
    "name": ".NETCoreApp,Version=v6.0/win-x86"

Edit: following up, you can also look for a pair of .exe and .dll files with the same name, try opening the DLL file in notepad and search for NETCoreApp, you should find something like this:

.NETCoreApp,Version=v6.0