When Wren will not start up make sure that it was installed properly, that is:
When an ASIO device is being used things may not work when the ASIO sample rate differs from the Wren sample rate. Check the Settings Screen F3 for this.
Had a user report that the program would not run in Windows 7. Turned out his antivirus was blocking it as an unsigned program that was downloaded from the web … with a message saying:
Had another user report repeatedly popped up access violations. It seems that this can be caused by the PortAudio DLL (or Wren's interaction with it most likely). You can read more about this on an electro-music.com forum thread.
When the startup screen appears and disappears again and Wren does not start try to temporarily rename the espeak_sapi.dll to _espeak_sapi.dll, when that helps I'd like to know about it, please send me the Wren.log file then (it is in the Wren.exe folder created in the Installation process).
On some computers it was reported that when an audio input was selected PortAudio refused to work (reporting an error on opening the input stream). For Wren releases after 2020.6.24.0 it is possible to explicitely select '~nothing~' for the device, this may help.
From time to time users are discovering exciting new bugs, please let me know about any failures. For this please go to the Wren Debug Screen F5, Wren logs some information there. When you right click on it you can highlight the text, and then with another right click copy it. At times I will ask for the information present there to help troubleshoot issues. By default this information is written to a log file in the Wren application directory as well, look for wren.log.
Also see General_troubleshooting.