For a long time we thought it was a problem of cron, or workflow (related closed #5575 ), but @vovpff realized that the problem was the failure to update the contacs, accounts and so on.

Yesterday I've buy a new hosting in Register.it italian hoster, but even in this hosting the results were the same.
Just buy a new shared hosting on Siteground, and being proceed to normal installation via softaculous, installation was good but issue remain!

So I can deduce that the problem is in Yetiforce 4.2.0 package, and also in its installation via Softaculous.
If someone has taken special precautions before, during or after the installation, or has not had any kind of problem using that particular hosting provider, please tell this community, so that me and other users like me in the same problem can finally use this crm.
Try to install the package downloaded from github and not install via Softaculous
I have already tried many times with the same result. I also tried version 4.1, same thing. I'm trying to install version 4.0, but after installation I can not get in any way, not even with admin-admin, now it gives me "I have already tried many times with the same result. I also tried version 4.1, same thing. I'm trying to install version 4.0, but after installation I can not login in any way, not even with admin-admin, now it gives me"Invalid username or password"
I've also reset manually user & pwd in db with:
user_password: $1$ad$hsl2kfybnrnbxba.b.wwv.
user_hash: 21232f297a57a5a743894a0e4a801fc3
but nothing to do.
Sorry, all zip releases download give error:
This XML file does not appear to have any style information associated with it. The document tree is shown below.
On all my tests I've faound a release that work: the 3.4.0 (downloaded via sourgeforce)

But when I try to update to 3.4.1427 to raise to latest release, I've an sql error:
Error!!!
SQLSTATE[42S02]: Base table or view not found: 1146 Table 'irnndaeb_yeti34.vtiger_firstname' doesn't exist Failed to prepare SQL: SELECT firstnameid, firstname FROM vtiger_firstname ORDER BY sortorderid
and when logout same issue user and password. I'm trying with your @vovpff zip file
@vovpff I'm sorry but also your file doesn't work!
@centoasa this is very strange...
and the interesting thing is that I tried on 3 different hosting.
I have just buy a new hosting space on A2 www.a2hosting.com and through softaculous I installed again. Again it does not work.
Today with @vovpff we’ve reached to solve but its installation was only on local machine, so he can’t solve this great issue.
yesterday we tried to install fresh 4.2.0 to @centoasa hosting and I noticed what installation process takes about 10 seconds. Some server requirements aren't met.
At my local machine (server) installation takes about 10-20 minutes.
Install the latest development version, it is possible that these problems have already been fixed
@mariuszkrzaczkowski composer included to latest dev?
As @centoasa said there are not possible to download old versions from github Yeti releases page.
@vovpff your is a local installation with LAMP
mine is a shared hosting installation. All my installation as prestashop, Suitecrm, vtiger, sugarcrm, wordpress, has not took no more than 2 minutes
@mariuszkrzaczkowski how can I download the development version, and how can I install it?
@mariuszkrzaczkowski
The links that you have provided refer to the stable versions, which are just those that do not work.
@mariuszkrzaczkowski releases on github looks like crashed:

Sourceforge is ok!
I've been saying this for many days, but none of the developers have heard me
Files updated
Installed the 4.2.0 complete, always the same problem of unregistered updates of contact, account....), after done update via zip file 4.2.0 _to_ 4.3.0 _rc7. zip
The contact edit buttons disappear
SOLVED

the nd_pdo_mysql was not flagged!
Now all works well!
Merry Christmas to all!
Note: I suggest add php modules requested in requirement page.

All the problems I had previously was precisely for this reason: the module you indicate was activated, but nowhere do you talk about the module nd_pdo_mysql
mysql and nd_pdo_mysql this is the same
Most helpful comment
SOLVED

the nd_pdo_mysql was not flagged!
Now all works well!
Merry Christmas to all!