the good old "no active checks on server" problem

[MrPurple]

First of all, zabbix is a wonderfull monitoring software, we used it without any problem, until now.

Okay guys, before you ask, yes i searched the board and i think i tried every single solution on stackoverflow etc

I am pulling my hair out a few days now. I am using a zabbix server without about 30 clients and everything is working perfectly. Now i wanted to add a random linux machine to zabbix and it just wont work.
Setup:
Server: 3.2.8
Client: 3.2.11 on Debian 9

The funny part is, that i copied the zabbix_agent.conf from another working zabbix agent and just changed the hostname. (yes, the hostname is correct set as machine name and hostname, no differences here)

zabbig_agent.conf:

PidFile=/var/run/zabbix/zabbix_agentd.pid
LogFileSize=0
LogFile=/var/log/zabbix-agent/zabbix_agentd.log
Server=192.168.99.17
ServerActive=192.168.99.17:10051
Hostname=MACHINE01

i added the client on the zabbix server at Configuration - Hosts - Create Host and entered the exact same hostname as in the config. i even checked the MySQL database on the server and checked if the hostname is correctly set.

the agent service starts without an error but on the server i never get any data. The agent logfile ( /var/log/zabbix-agent/zabbix_agentd.log) says:

320:20180111:164744.197 Starting Zabbix Agent [MACHINE01]. Zabbix 3.2.11 (revision 76339).
   320:20180111:164744.219 **** Enabled features ****
   320:20180111:164744.219 IPv6 support:          YES
   320:20180111:164744.219 TLS support:           YES
   320:20180111:164744.219 **************************
   320:20180111:164744.219 using configuration file: /etc/zabbix/zabbix_agentd.conf
   320:20180111:164744.222 agent #0 started [main process]
   323:20180111:164744.250 agent #3 started[listener #2]
   321:20180111:164744.253 agent #1 started [collector]
   322:20180111:164744.255 agent #2 started[listener #1]
   324:20180111:164744.268 agent #4 started[listener #3]
   325:20180111:164744.274 agent #5 started [active checks #1]
   325:20180111:164744.306 no active checks on server [192.168.99.17:10051]: host [MACHINE01] not found

I just dont get it. Did i forget to set something on the server? As i said, the exact same agent config works on all the other linux machines.

[MrPurple]

okidoki, finally i found the problem. In my case iam using the SQLITE Proxy version which destroyed domehow its sqlite database file so it couldnt update the lists from the zabbix server. In my case all old configurations (hosts) worked perfectly, but new ones just wont sync in the proxy database. You can find this hints in the proxy log which will write a line like:

 failed to update local proxy configuration copy: database error

and/or

[Z3005] query failed: [0] attempt to write a readonly database [insert into globalmacro (globalmacroid,macro,value) values (2,'{$SNMP_COMMUNITY}','public');

In this case just drop the sqlite database and create it new with the given zabbix schema. basically just follow the zabbix proxy installation guide on how to create the database. restart the proxy, voila.