No. I downloaded yesterday everything from the website and Newsletter from wordpress plugins directory. One thing that comes into my mind is that i installed and enabled plugins before i’ve installed and enabled the Newsletter itself. Can it be the issue here?
Hi, other plugin should not affect the saving of a subscriber. Try to enable the logging at debug level (on diagnostic panel) and check the files generated on wp-content/logs/newsletter/ folder (or send them to me at firstname.lastname@example.org after a couple of saving went wrong. If the log does not report enough information, I’ll ask you if it’s possible to have an admin account so I can debug the saving operation directly.
Eventually, try to deactivate and reactivate the plugin again.