Invalid UTF-8 character to ampersand, skip it

Hi,

I have a fresh install with:
Debian 10.3
Freeswitch 1.10.2
FusionPBX 4.4.11
(with mysql as db backend)

System works fine for the first shot. But I get many warnings like that:

2020-02-28 00:42:25.091974 [WARNING] sofia_reg.c:1793 SIP auth challenge (REGISTER) on sofia profile 'internal' for [10@mydomain.com] from ip 101.102.103.104
2020-02-28 00:42:25.391902 [WARNING] switch_xml.c:2563 Invalid UTF-8 character to ampersand, skip it
2020-02-28 00:42:25.391902 [WARNING] switch_xml.c:2563 Invalid UTF-8 character to ampersand, skip it
2020-02-28 00:42:25.391902 [WARNING] switch_xml.c:2563 Invalid UTF-8 character to ampersand, skip it
2020-02-28 00:42:25.391902 [WARNING] switch_xml.c:2563 Invalid UTF-8 character to ampersand, skip it
2020-02-28 00:42:25.691975 [WARNING] switch_xml.c:2563 Invalid UTF-8 character to ampersand, skip it
2020-02-28 00:42:25.691975 [WARNING] switch_xml.c:2563 Invalid UTF-8 character to ampersand, skip it
2020-02-28 00:42:25.691975 [WARNING] switch_xml.c:2563 Invalid UTF-8 character to ampersand, skip it
2020-02-28 00:42:25.691975 [WARNING] switch_xml.c:2563 Invalid UTF-8 character to ampersand, skip it
2020-02-28 00:42:25.991970 [WARNING] sofia_reg.c:1793 SIP auth challenge (REGISTER) on sofia profile 'internal' for [10@mydomain.com] from ip 101.102.103.104
2020-02-28 00:42:26.291923 [WARNING] switch_xml.c:2563 Invalid UTF-8 character to ampersand, skip it
2020-02-28 00:42:26.291923 [WARNING] switch_xml.c:2563 Invalid UTF-8 character to ampersand, skip it
2020-02-28 00:42:26.291923 [WARNING] switch_xml.c:2563 Invalid UTF-8 character to ampersand, skip it
2020-02-28 00:42:26.291923 [WARNING] switch_xml.c:2563 Invalid UTF-8 character to ampersand, skip it
[...]

Do you have any hint for me to solve this?

Best regards, Thorsten

I tracked it down: When using german umlauts like ö or ä or ä in the fields Effective Caller ID Name or Outbound Caller ID Name in extension configuration the error occurs. When using oe instead ö it works fine without these warning messages.

The error does not occur in the following setup:

Debian: 10.1
Freeswitch: 1.10.1
FusionPBX: 4.4.8

Maybe someone could check this in his setup to find out if this is an error within FusionPBX.