Hi,

03/11/2015 01:20 - Alex wrote:
> (...)
> Can't perform POST on https://cloud.otrs.com/otrs/public.pl: 500 read timeout

a (registered) system sends some data to the producer/manufacturer of OTRS.
you can find the data in Admin - System Registration.

If you receive this error you have:
- no internet connection via https
- a non or wrong configured proxy
- cloud.otrs.com is down
... maybe more?

> What exactly is the software trying to "POST" to https://cloud.otrs.com/otrs/public.pl?

for example:
https://otrs.github.io/doc/api/otrs/3.3/Perl/Kernel/System/Registration.pm.html

> Should I concerned about these entries in the log?

I would. You can ignore it, but I would just fix it. There is a script
for checking the CloudServices. 
see http://www.otrs.com/release-notes-otrs-help-desk-4-patch-level-6/?lang=es

> Also, since upgrading to OTRS ver 5.x, when closing a ticket, a subject field
>
> for the close note has now appeared and is mandatory? Is there any
> way to revert this to the previous behavior where just a note entry is enough?

Check sysconfig for this. Notes can be enabled/disabled and since OTRS4 (?) optional


Regards,

-- 
Florian