michcio29 essential_v6.6.1_2019-12-03_16-30-45.tar.gz essential_v5.10.11_2019-12-03_17-32-51.tar.gz I can install without any problems.
jvstratum Hi, Please raise a support ticket via Acyba's website: https://www.acyba.com/contact-us.html It would be helpfull to include login credentials for your backend and a link to this thread.
michcio29 For other people for the same issue please try to fix the AcyMailing DB tables using the following feature of AcyMailing
Alexandre Hi, Please contact us through our contact form and mention this thread in your email. We will have a look at it 😉