Hi,
There is a little bug, I am sorry for the inconvenience. Could you please go to the CMSModules folder and open the web.config file?
Then please find the section where the path is like "Newsletter/something" (3 occurrences). Please add "s" to the
Newsletter - there is a typo and the letter is missing there, so the path would be like "Newsletter
s/something".
I hope it will help.
Best Regards,
Juraj Ondrus