Multiple Revit Instances opening

[kathryn]

Every time I open a new Revit file or or family, it opens it in a new complete new window/ Revit instance. Revit 2025 is so screwed up.

[jay_colcombe]

Are you double clicking from File Explorer?

When opening a project or family from Windows explorer, a new session of Revit is opened (autodesk.c...

The solution from other threads and the links is;

1. Open the Registry Editor (Start > Run > Regedit > OK).
2. Browse to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.rvt
3. Delete the subfolder “UserChoice” from the registry branch.

[RSomppi]

It's not recommended to open files by double clicking on them in File Explorer.

See this other thread for a solution:

https://forums.autodesk.com/t5/revit-architecture-forum/revit-2020-bug-or-feature-new-instance-of-re...

[joshpAZD9W]

Thank you Jay. This has been happening since installing the latest PyRevit and your tip fixed it perfectly.

To anyone triggered and wanting to tell us all about "best practice" or Autodesk's advice on opening files I have two points to make:

1. Windows File Explorer is not a great file manager but it does allow searching. We are a small business and have a lot of smaller projects/family files that are sometimes tedious to find using the Open dialog in Revit. I use Windows to find files that I want opened in the current Revit instance all the time; and
2. Windows is the host platform and Revit does not behave in an adequate manner. It is not a Windows problem. Autodesk doesn't name the exe files with unique names (i.e. Revit 2024.exe, Revit 2025.exe) and this unnecessarily 'confuses' the OS. Revit ought to have a dialog that asks the user which exe to use and which instance. Doubleclick is a fundamental feature of windowing systems going back to the first commonly used ones in the 80s and 90s and is a bare minimum for client applications to support. (No offence RSomppi. I know it is common practice to lecture people about double-clicking project files around here but it is a bit more nuanced than many would have us think. We are all Windows users and it is not unreasonable for us to expect a major software developer such as Autodesk to maintain applications that follow Windows conventions.

[bentbrandt]

Revit have been around for a few years now. Congratulations!

it's 2025 and this annoying problem should be fixed, please.

[TripleM-Dev.net]

Just drag the projectfile or family into the homescreen of Revit from the Explorer. No issue guessing if it will open in the correct Revit version.

[RSomppi]

Proper training should get rid of the problem until a solution is provided. It's quite simple to open a project from within the program instead of double clicking a file.

[bentbrandt]

It has changed since we installed Revit 2026.

It's not consistent -that's what's annoying. The past year, until now, I could double click to open a project in Revit 2025.4 which is good because we work in many different projects during a day. So it has nothing to do with propper training, but rather, Microsoft and Autodesk tripping each other up...

[RSomppi]

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@bentbrandt wrote:

it has nothing to do with propper training, but rather, Microsoft and Autodesk tripping each other up...

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I wouldn't be so sure. I was taught early to not double click files to open them and have never had a problem with opening files from within the program that I want to use them in. It works EVERY time.

[bentbrandt]

Good for you.

We don't have a time dial so it's not an option for us.

[RSomppi]

There's no time like the present to adapt a better workflow. That way, if it ever changes again, you won't even notice.

[RDAOU]

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@bentbrandt wrote:

Revit have been around for a few years now. Congratulations!

it's 2025 and this annoying problem should be fixed, please.

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@bentbrandt @kathryn 

Sorry to hear you are having trouble with that. This happens due to a messed up windows registry after multiple installs and uninstalls of the same product or multiple versions of it but the good news is that it is fixable.

Ask your IT to modify the Shell Open Command key and remove the multiple instance switch. (See image below the relevant keys below for both Revit.Family & Revit.Projects...repeat for Revit.Templates if you wish to open these in the same running session)

PS: If you are doing it yourself, please consider backing up the registry before proceeding

[bentbrandt]

Thank you RDAOU for providing a relevant solution! I will try this 🙂

[RDAOU]

you are welcome. Let us know how it works out for you

[bentbrandt]

I backed up the registry and tried to edit it myself (my IT guy did not respond when I said Registry editor, and could not recall ever learning about it 😮 )
but could not identify a "multiple instance switch" only the path "C:\Program Files\Autodesk\Revit 2026\Revit.exe" /dde in Shell Open Command.

I found that deleting the “UserChoice” as suggested by jay_colcombe in the first answer above did the trick 🙂
Thanks to everyone who posted suggestions to solve this! 😀

[RSomppi]

You're welcome.