Error when importing type 'http://www.appian.com/ae/types/2009#HttpAuthenticationBasic'

Hi All,

While starting the Apache server on 18.3 i am getting below error :

2018-10-26 10:05:56,941 [ForkJoinPool-1-worker-9] INFO com.appiancorp.rdbms.datasource.BusinessDataSourceValidator - Validating data sources.
2018-10-26 10:06:23,647 [localhost-startStop-1] INFO com.appiancorp.plugins.PluginLoader - Appian Plug-in Framework starting for directory [/usr/local/appian/_admin/plugins]
2018-10-26 10:06:46,437 [localhost-startStop-1] ERROR com.appiancorp.type.config.xsd.XsdImporter - Error when importing type 'www.appian.com/.../2009. XSD: <xs:complexType name="HttpAuthenticationBasic">
<xs:annotation>
<xs:appinfo source="www.appian.com/.../2009">
<ns2:Metadata xmlns:ns2="www.appian.com/.../2009">
<ns2:Flags>HIDDEN</ns2:Flags>
<ns2:history/>
</ns2:Metadata>
</xs:appinfo>
</xs:annotation>
<xs:sequence>
<xs:element form="unqualified" minOccurs="0" name="username" type="tns:ScsField"/>
<xs:element form="unqualified" minOccurs="0" name="password" type="tns:ScsField"/>
<xs:element form="unqualified" name="preemptive" type="xs:boolean"/>
</xs:sequence>
</xs:complexType>

Any help would be appreciated.

Regards

Abhay