In Zabbix 1.8.17 we used external checks which look like this:

http_extend[ -l -t {$TIMEOUT} -u 'http://

{IPADDRESS}:80/' -r '(Impressum)' -s -h www.foooooo.de]

After the migration it looks like this:

http_extend["{HOST.CONN}", -l -t {$TIMEOUT} -u 'http://{IPADDRESS}

:80/' -r,'(Impressum fuer Foo)',-s,-h,www.foooooo.de]

This doesn't look dramatic, but the type of invocation changed.
Like many unix tools our tool uses getopt.h.

In 1.8.17 the tool got 10 parameters in the argv-array and the single quotes are ignored.
In 2.0.9 the tool gets only two parameters argv-array (

{HOST.CONN}

and "-l -t {$TIMEOUT} -u 'http://

{IPADDRESS}

:80/' -r,'(Impressum)',-s,-h,www.foooooo.de").
Therefore getopt is not capable to parse the arguments correctly and the items changes to "not supported" status.

The migration script should:
Replace all whithespaces by "," if they are not inside a pair of single or double quotes.

Note:
It would be great if the parameters "not supported" items are logged with detailed information regarding the arguments and the name of the host/item which invokes this external check.