When I replace Template1 by Template2 on a host (unlink & add template), I've got an error if graph exist.
My workaround is: unlink template, save, remove graph, link new template.

My problem is:
When I replace template1 by template2, the result is not the same in 1.8.3 and 1.8.4

• in Zabbix 1.8.3, I've got an error on the screen about the new template linkage and graphs ==> OK (can see what is wrong on linkage)
• in Zabbix 1.8.4, I've got an empty screen (just Zabbix header and menu) with a warning about error on page ==> NOK (I don't know what is wrong, if the change was done or not).
  The error in the page for IE 8 is :

Webpage error details
User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; xs-JC2aYBYDH9Y;ChBAE5; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; MS-RTC LM 8; MS-RTC EA 2; AskTbFXTV5/5.9.1.14019)
Timestamp: Tue, 29 Mar 2011 14:32:17 UTC
Message: Object expected
Line: 18
Char: 1
Code: 0
URI: https://zabbixserver/hosts.php