About Dotfuscator Community & Visual Studio

PreEmptive Protection - Dotfuscator provides comprehensive .NET application protection that easily fits into your secure software development lifecycle. Use it to harden, protect, and prune desktop, mobile, server, and embedded applications to help secure trade secrets and other intellectual property (IP), reduce piracy and counterfeiting, and protect against tampering and unauthorized debugging. Dotfuscator works on compiled assemblies without the need for more programming or even access to source code.

PreEmptive Protection - Dotfuscator

Why protection matters

It's important to protect your intellectual property (IP). Your application's code contains design and implementation details, which can be considered IP. However, applications built on the .NET Framework contain significant metadata and high-level intermediate code, making them easy to reverse engineer, just by using one of many free, automated tools. By disrupting and stopping reverse-engineering, you can prevent unauthorized IP disclosure, and demonstrate that your code contains trade secrets. Dotfuscator can obfuscate your .NET assemblies to hinder reverse-engineering, while maintaining original application behavior.

It's also important to protect the integrity of your application. In addition to reverse-engineering, bad actors may attempt to pirate your application, alter the application's behavior at run time, or manipulate data. Dotfuscator can inject your application with the capability to detect and respond to unauthorized uses, including tampering, third-party debugging, and rooted devices.

For more information on how Dotfuscator fits into a secure software development lifecycle, see PreEmptive Solutions' SDL App Protection page.

About Dotfuscator Community

Your copy of Microsoft Visual Studio includes a copy of PreEmptive Protection - Dotfuscator Community, free for personal use. (This free version was previously known as Dotfuscator Community Edition or Dotfuscator CE.)

For instructions on how to install the version of Dotfuscator Community included with Visual Studio, see the Installation page.

Dotfuscator Community offers a range of software protection and hardening services for developers, architects, and testers. Examples of .NET Obfuscation and other Application Protection features included in Dotfuscator Community are:

  • Renaming of identifiers to make reverse-engineering of the compiled assemblies more difficult.
  • Anti-tamper to detect the execution of tampered applications and terminate or respond to tampered sessions.
  • Anti-debug to detect the attachment of a debugger to a running application and terminate or respond to debugged sessions.
  • Anti-rooted device to detect if the application is running on a rooted Android device and terminate or respond to sessions on these devices.
  • Application expiration behaviors that encode an "end-of-life" date and terminate expired application sessions.

For details on these features, including how they fit into your application protection strategy, see the Capabilities page.

Dotfuscator Community offers basic protection out-of-the-box. Even more application protection measures are available to registered users of Dotfuscator Community, and to users of PreEmptive Protection - Dotfuscator Professional, the world's leading .NET Obfuscator. For information about enhancing Dotfuscator, see the Upgrades page.

Getting started

To begin using Dotfuscator Community from Visual Studio, type dotfuscator into the Search Box (Ctrl+Q).

You can also get the latest version of Dotfuscator Community from the Dotfuscator Downloads page on preemptive.com.

Upgrade from Dotfuscator Community 5

Learn how to upgrade to PreEmptive Protection - Dotfuscator Community 6.

Depending on your installation history and version of Visual Studio, you may be currently running Dotfuscator Community 5, the prior major version. If so, you should upgrade, because it is important to ensure your code is being given the latest protection measures. Upgrades are available at no charge.

This article explains how to determine what version you currently have, how to upgrade to version 6 if necessary, and what features have been replaced or removed between the two versions.

Determine the Dotfuscator version

If you are unsure what version of Dotfuscator you are running, you can determine the version by doing one of the following options:

  • Launch the Dotfuscator Community graphical user interface (GUI) by going to Visual Studio's Tools menu and selecting PreEmptive Protection - Dotfuscator Community.

    From the Dotfuscator GUI, open the Help menu, and select About... to display the About screen.

    This screen lists Dotfuscator's version.

  • If you have Dotfuscator integrated into your build with the command-line interface (such as with Xamarin apps), you can also check your build logs for a line like the following example:

    Dotfuscator Community Version

    You may need to increase your build's verbosity in order to see this text. For Visual Studio, see Verbosity Settings.

The first integer of the version, before the first dot ., indicates Dotfuscator's major version. If the first integer is 5, then you should perform the upgrade steps on this page, so that you can take advantage of the latest Dotfuscator 6 features and protection updates.

Upgrade instructions

This section includes sets of instructions for upgrading typical usages of Dotfuscator Community from version 5 to version 6.

Install Dotfuscator 6

Dotfuscator Community is distributed as an extension for Visual Studio. The instructions to install Dotfuscator 6 vary by which version of Visual Studio you have:

  • Visual Studio 2019 Dotfuscator Community 6 is included in later versions of Visual Studio 2019 (version 16.10.0 and later). Update Visual Studio 2019 to the latest version. Updating Visual Studio automatically upgrades any Dotfuscator Community 5 installation to Dotfuscator Community 6.

    • If you do not have Dotfuscator installed already, update Visual Studio first and then see Installation.

    • In addition to the releases with Visual Studio, you can always get the latest versions of Dotfuscator Community from the Dotfuscator Downloads page.

  • Visual Studio 2017 This version of Visual Studio only shipped with Dotfuscator Community 5. However, you can install or upgrade to Dotfuscator Community 6 by going to the Dotfuscator Downloads page and selecting the appropriate download link.

    Run the downloaded .vsix file and follow the prompts to install Dotfuscator Community 6 into Visual Studio. Existing Dotfuscator Community 5 installations is also be upgraded.

  • Earlier versions of Visual Studio Dotfuscator Community 6 is not supported in these versions of Visual Studio. We recommend upgrading to a newer version of Visual Studio, or upgrading from Dotfuscator Community to Dotfuscator Professional.

If you had previously registered Dotfuscator Community 5, that registration is automatically converted the first time you run Dotfuscator Community 6.

Update paths to the CLI

If you previously used Dotfuscator 5's command-line interface (CLI) to protect your app, you need to update the path to the CLI in any projects and build scripts that reference it. It includes projects that use Dotfuscator Community's Xamarin integration.

The reason a path to Dotfuscator's CLI may now be invalid is because the names of some of the executables installed with Dotfuscator Community have changed in Dotfuscator 6. This change makes these executable names the same across Dotfuscator Community and Dotfuscator Professional.

Executable for... Dotfuscator 5 Dotfuscator 6
GUI dotfuscator.exe dotfuscatorUI.exe
CLI dotfuscatorCLI.exe dotfuscator.exe


The CLI path may also be invalid if you upgrade between major versions of Visual Studio or switch Visual Studio editions, as the Dotfuscator CLI is installed under Visual Studio's installation directory. The symptoms and solution listed below also apply to this scenario.

If your build is using an invalid Dotfuscator CLI path, you may get errors such as one of the following examples:

'"[...]\PreEmptiveSolutions\DotfuscatorCE\dotfuscatorCLI.exe"' is not recognized as an internal or external command, operable program or batch file.

The command ""[...]\PreEmptiveSolutions\DotfuscatorCE\dotfuscatorCLI.exe" Dotfuscator.xml" exited with code 9009.

When the DotfuscatorXamarinEnabled property is 'true', the Dotfuscator command line interface specified by DotfuscatorXamarinCliPath ('[...]\DotfuscatorCE\dotfuscatorCLI.exe') must exist.

To update your build to use the correct CLI path:

  1. Start the Dotfuscator Community GUI by going to Visual Studio's Tools menu and selecting PreEmptive Protection - Dotfuscator Community.

  2. In the Dotfuscator Community GUI, go to the Tools menu and select Dotfuscator Command Prompt.

  3. In the command prompt that opens, type where dotfuscator.exe. Copy the first path displayed to a plain text document for later reference. This path is the new path to Dotfuscator Community 6's CLI.

  4. Open the project or build configuration as appropriate for your build system.

    • For Visual Studio projects, open the project file (.csproj, .vbproj, or .fsproj) as plain text. Open a project file in Visual Studio.

    • If you previously used Dotfuscator Community's Xamarin integration to protect a Xamarin app, recall that Dotfuscator is integrated into each individual app project (such as MyProject.Android.csproj and MyProject.iOS.csproj) separately and not into shared library projects. Update all of the app projects that are currently using Dotfuscator.

  5. Locate any places within your project or build configuration where an old path to Dotfuscator Community 5's CLI is used. It typically is a path ending in dotfuscatorCLI.exe.

    • When updating a project using Dotfuscator Community's Xamarin integration, the old path is located between the <DotfuscatorXamarinCliPath> and </DotfuscatorXamarinCliPath> tags.
  6. Replace the old paths located in step 5 with the new path you noted in step 3.

    If one of the old paths is not an absolute path, then you should adjust the new path appropriately based on the context. In the example below, the VSInstallDir environment variable was used in the old path, so the corresponding new path should do the same.

    • New path from step 3: C:\Program Files (x86)\Microsoft Visual Studio\2019\Preview\Common7\IDE\Extensions\PreEmptiveSolutions\DotfuscatorCE\dotfuscator.exe
    • Old path in project file: %VSInstallDir%\Common7\IDE\Extensions\PreEmptiveSolutions\DotfuscatorCE\dotfuscatorCLI.exe
    • New path in project file: %VSInstallDir%\Common7\IDE\Extensions\PreEmptiveSolutions\DotfuscatorCE\dotfuscator.exe
  7. If you are using a source control system, such as Git, then ensure the changes from step 6 are reflected in that system. Distribute these changes to the rest of your team as may be appropriate for your system and organization.


Because dotfuscator.exe refers to the graphical user interface (GUI) in Dotfuscator 5 but refers to the command line interface (CLI) in Dotfuscator 6, be careful when updating build scripts shared across multiple machines.

A machine with Dotfuscator 5 installed that runs a script updated for Dotfuscator 6 causes the script to launch the graphical user interface, instead of the intended command line interface. This may cause the build to succeed despite not applying Dotfuscator's protection, meaning your output packages will NOT be protected.

In other cases, it could instead cause a build failure.

To avoid these scenarios, upgrade Dotfuscator Community from version 5 to version 6 across all of your machines and build scripts at the same time.

Upgrade Dotfuscator config files

All Dotfuscator config files (such as Dotfuscator.xml) that were created prior to Dotfuscator 6 needs to be upgraded.

If you try to run the Dotfuscator CLI with an old configuration file, you get errors like the following examples:

Dotfuscator Engine Initialization error: PreEmptive Analytics, Authenticode signing, and the Introduce Explicit Method Overrides setting are no longer supported. Please open your Dotfuscator config in the Config Editor which automatically upgrades it.


You receive this error and need to upgrade your config file even if you were not using the features mentioned.

To upgrade a config file:

  1. Launch the Dotfuscator Community graphical user interface (GUI) by going to Visual Studio's Tools menu and selecting PreEmptive Protection - Dotfuscator Community.

  2. Open the Dotfuscator config file in question (Ctrl+O).

  3. The following message is displayed in the Build Output tab:

    PreEmptive Analytics, Authenticode signing, and the Introduce Explicit Method Overrides setting are no longer supported. The associated settings have been removed. Please save your upgraded Dotfuscator config.

  4. Save the updated Dotfuscator config file (Ctrl+S).

  5. If you are using a source control system, such as Git, then ensure the changes to the Dotfuscator config file are reflected in that system. Distribute these changes to the rest of your team as may be appropriate for your system and organization.

Update Xamarin Integration

If you integrated Dotfuscator Community 5 into your Xamarin project, one of the steps required you to download custom MSBuild targets and tasks, such as PreEmptive.Dotfuscator.Xamarin.targets. These targets and tasks have been updated in Dotfuscator Community 6, so you need to replace the old versions with the new versions.

To update your Xamarin integration files:

  1. Locate the directory where you initially downloaded these files. The example given in the instructions uses a subdirectory named PreEmptive.Dotfuscator.Xamarin, but you may have downloaded the files into a different directory, which may or may not also have files unrelated to Dotfuscator.

  2. In the directory located in step 1, delete the files related to the Dotfuscator Xamarin integration.

  3. Download the ZIP file linked at the current version of the following User Guide section: Download the custom set of MSBuild Targets and Tasks for Dotfuscator.

  4. Extract the contents of the ZIP file to the same directory as noted in step 1.

  5. If you are using a source control system, such as Git, then ensure the removal of the old files and addition of the new files are reflected in that system. Depending on the kind of system, these changes may appear as files changing contents, rather than being replaced. Distribute these changes to the rest of your team as may be appropriate for your system and organization.

Other subsections on this page also apply to Xamarin projects, so be sure to review the rest of this page's instructions.

Update references to attribute libraries

Dotfuscator allows you to configure certain features via .NET attributes in your source code. If your projects were using such attributes, you may need to update them to address changes in Dotfuscator 6.

Obfuscation attributes

There have been no changes to the Obfuscation Attributes. These attributes are defined in the .NET base class libraries, and Dotfuscator Community 6 continues to honor them.

Check Attributes

The library containing the Check Attributes has changed. In Dotfuscator Community 5, it was distributed as a file alongside Dotfuscator itself. Starting in Dotfuscator Community 6, it is instead distributed as a public NuGet package.

If you try to build a Visual Studio project that still references the old location, you may get errors like the following examples:

The type or namespace name 'PreEmptive' could not be found (are you missing a using directive or an assembly reference?)

The type or namespace name 'TamperCheckAttribute' could not be found (are you missing a using directive or an assembly reference?)

You may also get this warning:

Could not resolve this reference. Could not locate the assembly "PreEmptive.Attributes". Check to make sure the assembly exists on disk. If this reference is required by your code, you may get compilation errors.

To update your project to use the new location:

  1. Remove the project's assembly reference to PreEmptive.Attributes.dll.

  2. Add the NuGet package reference PreEmptive.Protection.Checks.Attributes to the project. The package is available on the default NuGet feed, nuget.org.

Each Check Attribute's ExtendedKey parameters have also been removed. These parameters were ignored in Dotfuscator Community 5, but if your source code used them regardless, remove these usages in order for your project to compile.

Instrumentation attributes

Instrumentation attributes were used to configure the PreEmptive Analytics feature in Dotfuscator 5. However, PreEmptive Analytics has been removed in Dotfuscator 6; see the Removed Feature subsection PreEmptive Analytics. As a result, the instrumentation attributes have also been removed.

If you try to build a Visual Studio project that used instrumentation attributes, you may get the same kinds of errors and warnings as noted in Check Attributes, though the attribute names differ (for example, FeatureAttribute instead of TamperCheckAttribute).

If you try to run Dotfuscator on already-built assemblies that contain usages of instrumentation attributes, you get errors like the following examples:

The PreEmptive.Attributes.FeatureAttribute attribute (annotating SomeNamespace.SomeType::SomeMethod) is not recognized by this version of Dotfuscator.

To fix these problems, remove all usages of instrumentation attributes from your source code. You also need to remove the assembly references to the library that defined the attributes, PreEmptive.Attributes.dll. (If you were also using the Check Attributes that were defined in this library, they have moved; see Check Attributes above.)

Removed features

Dotfuscator Community 6 introduces breaking changes from Dotfuscator Community 5. If you have been using Dotfuscator Community 5, this section describes how to deal with the changes that might require build modifications or affect Dotfuscator's output.

A full list of the changes is available in the changelog.

PreEmptive Analytics

Dotfuscator 6 does not support PreEmptive Analytics, including Check Telemetry. However, Checks themselves (including Application Notification and Check Actions) are still supported.

To use Dotfuscator 6, upgrade your configuration file to remove the PreEmptive Analytics settings.

If you were using in-code attributes to configure PreEmptive Analytics, remove them from your source code and rebuild your input assemblies before Dotfuscator 6 can protect those assemblies.

If you were using Check Telemetry to report when a Check detects an invalid state (such as when tampering is detected), you can replace it with a custom Application Notification that reports the incident to Azure Application Insights or another service of your choice.

Unsupported application types

The following application types are no longer supported in Dotfuscator 6:

  • Windows Phone
  • WinRT (Windows 8 apps)
  • Silverlight
  • Unity (game engine)

Additionally, Universal Windows Platform (UWP) apps are only supported for Xamarin scenarios.

To protect other kinds of UWP apps, upgrade to Dotfuscator Professional and follow the Protect Your App instructions.

Unsupported inputs

Dotfuscator Community no longer supports Universal Windows Platform (UWP) .appx packages as inputs. You can continue to protect Xamarin apps targeting UWP with the Xamarin integration. To protect other kinds of UWP apps, upgrade to Dotfuscator Professional and follow the Protect Your App instructions.

Additionally, .xap packages can no longer be used as inputs because Silverlight is no longer supported.

Introduce explicit method overrides

The Renaming option to introduce explicit method overrides has been removed from Dotfuscator. To use Dotfuscator 6, upgrade your configuration file to remove this setting.

Full documentation

See the full Dotfuscator Community User Guide at preemptive.com for detailed usage instructions, including how to start using the Dotfuscator Community user interface.