According to RFC 3986: Uniform Resource Identifier (URI): Generic Syntax, 3.2.2 Host https://192.168.000.155/ is not a valid URI.
Definition of a host name:
host = IP-literal / IPv4address / reg-name IPv4address = dec-octet "." dec-octet "." dec-octet "." dec-octet dec-octet = DIGIT ; 0-9 / %x31-39 DIGIT ; 10-99 / "1" 2DIGIT ; 100-199 / "2" %x30-34 DIGIT ; 200-249 / "25" %x30-35 ; 250-255So, 000 is not a dec-octet, thus 192.168.000.155 is not a valid host name.
Please use valid hostnames.
Additionally, DAVdroid has checked the hostname validity with new URL() instead of new URI(), causing it to accept the URL on the first dialog while crashing thereafter. This has been fixed.