I’ve downloaded PsychoPy Standalone 2026.2.3 on MacOS Tahoe 26.6.2. I haven’t been able to open the application even once, when opening there is a launch error.
Thank you for your help!
Did you have an older version of PsychoPy installed before? Sometimes the config settings break and you need to delete a hidden .cfg file so it reinitializes everything. See here: Need Help with Launch Error in PsychoPy - Seeking Solutions - #4 by eyeballologist
If this is a clean install, then no clue. Are you getting any specific error text?
I tried the same (Standalone 2026.2.3 to a MacOS Tahoe 26.6.2) and it didn’t open for me either, it was a clean install.
I downloaded Standalone 2025.2.3 and it did launch.
For those in-the-know, I got this little reminder from my Mac when it launched:
Support Ending for Intel-based Apps. This version of “PsychoPy” will not open in a future release of MacOS. Learn how to update to an Apple silicon version.
Oh dear [sigh] I wonder if Apple have done something to make software distribution harder again! 
I don’t actually have a Tahoe machine yet but 2026.2.3 is definitely fine on my ARM Sequoia laptop.
I assume your machine is ARM (M1/2/3 etc, not an old intel device that you’ve got Tahoe running on) because certainly the default file we recommend on the downloads page now is the ARM installer. We provide both the ARM and Intel versions on the GitHub Releases page (if you scroll down to the assets for your desired release).
So, assuming you have the default ARM installer and an ARM-base Mac, let’s see if there’s any more information to help us…
Could you do this (screenshots below):
- open a Finder window and then go to folder (Command-Shift-G)
- go to ~/Library/Application Support/psychopy4/
In there you will hopefully see a filelast_app_load.logand I’d like to know if that has any info in it please?
Thanks
Ok, here is the text from the log file. I hope it helps somehow.
Thanks for everyone’s help! I was able to fix my problem by downloading this StandalonePsychoPy-2026.2.3-macOS-arm64-3.11 (3).dmg from Github and changing my language preferences to only English.
Oh, apologies, when I read it I realise that I directed you to the log file for PsychoPy Studio, but you were referring to PsychoPy Standalone.
The equivalent file for Standalone is in ~/.psychopy3 and we’d really appreciate that file. From your comment @kasutaja123 I wonder if this is a language/locale issue - that would make sense if it only affects some people. Thanks for the info - it gives us something to try
My language prefs include a second language, too, but it is not the primary. Should I remove it to run Standalone 2026.2.3?
I managed to launch Standalone 2025.2.3 and I am fine with it for now, though.
Here is the text from that log:
2.4405 DEBUG Opening message catalog /Applications/PsychoPy.app/Contents/Resources/lib/python3.10/psychopy/localization/../app/locale/en_US/LC_MESSAGE/messages.mo for locale en_US
30.3267 WARNING Font Manager failed to load file /System/Library/PrivateFrameworks/FontServices.framework/Resources/Reserved/PingFangUI.ttc
30.4211 WARNING Font Manager failed to load file /System/Library/PrivateFrameworks/FontServices.framework/Resources/Reserved/PingFangUI.ttc
33.7389 INFO Calling psychopy.plugins.activatePlugins(), but no plugins have been found in active distributions.
33.9535 DEBUG PavloviaLoggedIn
============================ Updating package index ============================
Running command: /Applications/PsychoPy.app/Contents/MacOS/python /Applications/PsychoPy.app/Contents/Resources/lib/python3.10/psychopy/scripts/psychopy-pkgutil.py --app-pref-dir /Users/weitemieradamzachary/.psychopy3 update
Exception in thread Thread-6 (refreshPackageIndexTask):
Traceback (most recent call last):
File “threading.pyc”, line 1016, in _bootstrap_inner
File “threading.pyc”, line 953, in run
File “/Applications/PsychoPy.app/Contents/Resources/lib/python3.10/psychopy/app/plugin_manager/packageIndex.py”, line 299, in refreshPackageIndexTask
downloadPluginAssets()
File “/Applications/PsychoPy.app/Contents/Resources/lib/python3.10/psychopy/app/plugin_manager/packageIndex.py”, line 103, in downloadPluginAssets
for plugin in _packageIndex[‘available’][‘plugins’][‘packages’].values():
TypeError: ‘NoneType’ object is not subscriptable
50.6678 ERROR Package index file not found.