Hi there,
we run Zabbix for a large installation

1715 Hosts (mostly VMWARE via two vCenters)
179.671 Items, 7128 disabled (a lot of them networking related since we use several cisco ucs domains)
28.041 Triggers, 2168 disabled
1381,61 NVps

We changed templates to hold most of history data for 33d, now database seems to be nearly stable at 700GB.

-> everything works fine BUT!

----------Problem---------

If we try to change the template "Template VM VMware Guest" to store items for 33d (insted of default 90d) history the change is not processed an a blank site is shown.

Reproducable with:

Open Template
Click on Cluster name
Change "History storage period" to 33d
Click Update

-> we get a blank screen and changes are not applied

We can reproduce this with any kind of changing  the template, also disabling of the items
is not possible.

In our small testenvironment (exactly the same versions, no data in it but a few hosts) changes work perfectly

-> we think it's an issue because of the high amount of dtaa in our production environment,
approx. 1650 vmware guests are discovered via the templates....

-------------------------

There is no logdata inserverlog also when we left windows open for a night - no long queries etc...

In sslaccess log from frontend we see when performing the desribed case:

--Beginn of ssl_access.log---------------
172.22.64.1 - - [30/Dec/2018:23:19:18 +0100] "GET /items.php?form=update&hostid=10174&itemid=26965 HTTP/1.1" 200 62860
172.22.64.1 - - [30/Dec/2018:23:19:19 +0100] "GET /jsLoader.php?ver=4.0.3&lang=en_GB&showGuiMessaging=1 HTTP/1.1" 304 -
172.22.64.1 - - [30/Dec/2018:23:19:19 +0100] "GET /jsLoader.php?ver=4.0.3&lang=en_GB&showGuiMessaging=1&files[]=class.cviewswitcher.js&files[]=multiselect.js&files[]=items.js&files[]=servercheck.js HTTP/1.1" 304 -
172.22.64.1 - - [30/Dec/2018:23:19:19 +0100] "POST /jsrpc.php?output=json-rpc HTTP/1.1" 200 400
172.22.64.1 - - [30/Dec/2018:23:19:24 +0100] "POST /jsrpc.php?output=json-rpc HTTP/1.1" 200 62
172.22.64.1 - - [30/Dec/2018:23:19:25 +0100] "POST /items.php HTTP/1.1" 500 7890
172.22.64.1 - - [30/Dec/2018:23:19:26 +0100] "GET /jsLoader.php?ver=4.0.3&lang=en_GB&showGuiMessaging=1 HTTP/1.1" 304 -
172.22.64.1 - - [30/Dec/2018:23:19:26 +0100] "GET /jsLoader.php?ver=4.0.3&lang=en_GB&showGuiMessaging=1&files[]=class.cviewswitcher.js&files[]=multiselect.js&files[]=items.js&files[]=servercheck.js HTTP/1.1" 304 -
172.22.64.1 - - [30/Dec/2018:23:19:31 +0100] "POST /jsrpc.php?output=json-rpc HTTP/1.1" 200 62
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