Hi @la9arte,
When a critical error like this happens, you should receive an email sent to the overall site admin inbox – this is the email address set on the site under Settings > General as the main administrator.
An email like this will say that a critical error has happened on the site, and include a full stack trace at the bottom (a series of lines indicating what part of code on the site caused the crash).
Can you find this email and copy and paste the full stack trace into this thread?
If you cannot locate such an email, you can look under WooCommerce > Status on the “Logs” tab for a log file called “fatal-errors” and dated the date you tried the export. It will have a shorter version of the error report you can also copy and paste into your response here.
If you can’t find either, then the next step is a conflict test, which involves deactivating non-WooCommerce plugins and reverting to a standard theme, and trying the export -> then re-activating your theme and plugins one at a time, testing each time, to find the issue. You can read more about that here:
https://woocommerce.com/document/how-to-test-for-conflicts/
