Prevent Multiple Instances of 4D on Windows

Is there any way to prevent 4D to open Multiple instances on Windows, like 4D in 32 bit ?

If you doubleclick 4D in 32-bit mode and double click it again, it opens the same instance on Windows
4D 64-bit opens a new instance, sometimes this is nice but some times it isn’t.

The problem we have is that we have 4D running on terminal servers, when you click an icon in the taskbar it opens a 4Dlink file to open 4D and directly login to the 4D Server. Now some people click the icon again, but then the same 4Dlink file is open’t and the same client to login to the same server, we want to prevent this, so it opens the same instance you opened before, like 4D in 32 bit.

Is there any way ?

Don’t use 4D.exe but build an application (merged app).
They don’t allow instances.
As they automatically connect to a server and don’t allow creating new structures, etc, they also avoid confusion or miss usage.

Thanks Thomas for the quick answer.

I will try the merged app to see how it works.


Thank you for the tip Thomas.

Unfortunately, in our hosting situation: we host more than 300 different databases: but connect to them through a common 4D Remote on our RDS servers. Creating, and deploying 300+ separate built applications for us is not a possibility.

We need some other solution.

17 R5 might be your solution.

the client local cache has a 3 digit suffix,



which is derived from the full path of the application,
but incremented in case a collision is detected (i.e. the file inuse.txt is in it)

incidentally, this new system eliminates the need for a ClientLocal.

Thanks for the suggestion: this might help our situation: if we can get to R5.
(We’re generally more concerned with stability than with features, so we’re on dot versions)

I think 4D needs ~some kind~ of a configuration option for x64 client to configure between multi-launch vs single launch.