Where does VST3PluginTestHost store plugin parameters and other settings?

I’m using VST3PluginTestHost.exe to test a newly developed instrument plugin. I noticed that the test host stores all plugin parameters and other settings on exiting and restores them when running it again.
On one computer of mine, this works fine. On the other, however, there is no restoring of previous settings. The plugin always is loaded with its default settings. While debugging, I noticed that the getState() method of my processor instance and the getComponentState method of the controller instance never get called. Also, the plugin’s sample rate always is initialized to 11.025 Hz instead of the desired value of 44.100 Hz, and I can’t find any way to change this. When I load my plugin in a DAW, everything is fine, though. Plugins store and load their presets and use the project’s sample rate.
On my other computer with the very same project code, VST3PluginTestHost.exe behaves correctly. getState() and getComponentState() methods get called (and as a result, plugin’s settings are stored on exiting and restored when re-starting it) and the plugin’s samplerate is set as desired to 44.100 Hz.
I guess the test host’s parameter storage is corrupted, and I’d like to clear it. But I can’t find the place where VST3PluginTestHost.exe stores all this information, neither in the registry nor in any directory on disk. Uninstalling VST3PluginTestHost.exe and re-installing it didn’t help. But plugin settings and host configuration must be stored somewhere. But where?
I’d greatly appreciate any hints how to reset parameter storage. Many thanks in advance.
Regards, Michael

maybe on the machine with strange behavior you have no ASIO driver installed?
else the VST3PluginTestHost saves its last state in this folder:
C:\Users\USERNAME\AppData\Roaming\Steinberg\VST3PluginTestHost Standalone_64

Thanks for your answer.

On both machines there are ASIO drivers installed. On one machine (the one where VST3PluginTestHost works) it’s the driver of a Focusrite interface, on the second machine (a laptop where the test host behaves strangely) it is either the ASIO driver for a ESI U24XL interface or, when the interface is not connected, ASIO4all.

So this can’t be the reason for my problems.

BTW: In any other host, the sample rates of all ASIO drivers on both machines get set accordingly to the project’s settings in the host. When I set project’s sample rate to 44.100 Hz, my plugin will always be set to this sample rate. In VST3PluginTestHost.exe, however, I could’t find a way to set the sample rate. As a result, VST3PluginTestHost.exe sets the samplerate on one machine to 44.100 Hz (the desired value), on the other to 11.025 Hz (way too low), and I don’t know how to change this.


I found out where VST3PluginTestHost.exe stores configuration data in Windows: it places XML files in the folder %appdata%\Steinberg\VST3PluginTestHost Standalone_64. However, clearing this folder didn’t solve my problems. Patch parameters still are not restored when re-starting the host and sample rate is still set to 11.025 Hz. As mentioned, this happens on only one machine. The test host works fine on another machine. On both machines, the plugin (including ASIO driver) works fine when loaded into other hosts, so I don’t think there’s something wrong with my plugin or the ASIO environment.

JFTR: I’m using the latest version of VST3PluginTestHost.exe (3.4.0).

Now plugin parameters aren’t saved on neither machine :rage:
The problem occured out of the blue and I don’t know which change on my project caused the problem neither how to solve it. Deleting all files in %appdata%\Steinberg\VST3PluginTestHost Standalone_64 didn’t help.