When users try to upload attachments they are getting the following error.
SDM advanced availability configuration. This error happens when doing attachment from app servers URL but works if doing it directly on background server.
Release : 17.3
Component : SDM - Attachments
One possible reason is the CORS blocking on the background server. Check SDM-install\bopcfg\www\CATALINA_BASE\webapps\CAisd\WEB-INF\web.xml file on the background server and it should have
<param-name>cors.allowed.origins</param-name>
<param-value>https://sdm-app-server1:portnumber,https://sdm-app-server2:portnumber,...https://sdm-app-servern:portnumber
</param-value>
if it does not, change/save this web.xml file and recycle Tomcat/SDM on the background server