Service unavailable error

After the latest updates from CS Cart and AlexBranding I receive a lot of Sorry, Service Unavailable errors on front end and admin. I refresh 2-3 times and it works again, then click on different page and goes again in error and so on. I tried to open page source for errors but nothing appear. I have to mention that the website has the storefront closed and I tried to open the website with the key, also managed to open the store front and retried with differnet browser but got the same problem. Any ideas where to look at?
Thank you!

“Service Unavailable” is a generic error message and basing on it we cannot tell what can be wrong with your store.
I’d suggest you to enable development mode (Configuring CS-Cart — CS-Cart 4.17.x documentation) and show us the errrors.

Check server error logs. The error details should be there

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