No cahnges to Netwoks/Interfaces can be done

[GlukRazor]

In my Zentyal 3.4.7 I cannot apply canges to network interfaces settings - I always see error like:

The following modules failed while saving their changes, their state is unknown: network The following modules failed while saving their changes, their state is unknown: network at The following modules failed while saving their changes, their state is unknown: network at /usr/share/perl5/EBox/GlobalImpl.pm line 735 EBox::GlobalImpl::saveAllModules('EBox::GlobalImpl=HASH(0x95f5b20)', 'progress', 'EBox::ProgressIndicator=HASH(0x847a99c)') called at /usr/share/perl5/EBox/Global.pm line 95 EBox::Global::AUTOLOAD('EBox::Global=HASH(0x9610cf4)', 'progress', 'EBox::ProgressIndicator=HASH(0x847a99c)') called at /usr/share/zentyal/global-action line 32 eval {...} at /usr/share/zentyal/global-action line 30

I use this server installation for 3 years I think, but now it become unstable.