When opening the Virtual Agent the window is blank

When opening the Virtual Agent the window is blank.  we review the log for the preview of the topic the following exception appears:

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18:10:23.883: system topic is completed, conversationId 8bec4791dba50810fe5e2dcb0b961917
18:10:23.883 [Context] TopicName: system TopicId: 8bec4791dba50810fe5e2dcb0b961917 [ConversationImpl] topic_state TopicName=system TopicId=8bec4791dba50810fe5e2dcb0b961917 topicState=completed
18:10:23.881: topic_state TopicName=system TopicId=8bec4791dba50810fe5e2dcb0b961917 topicState=completed
18:10:23.820 [Context] TopicName: system TopicId: 8bec4791dba50810fe5e2dcb0b961917 [TaskStateManager] Executing task 0fec4791dba50810fe5e2dcb0b961918-init perform completed with payload null
18:10:23.818: Executing task 0fec4791dba50810fe5e2dcb0b961918-init perform completed with payload null
18:10:23.818 [Context] TopicName: system TopicId: 8bec4791dba50810fe5e2dcb0b961917 [TaskStateManager] Executing task 0fec4791dba50810fe5e2dcb0b961918-init perform confirm with payload null
18:10:23.817: Executing task 0fec4791dba50810fe5e2dcb0b961918-init perform confirm with payload null
18:10:23.816 [Context] TopicName: system TopicId: 8bec4791dba50810fe5e2dcb0b961917 [TaskStateManager] Executing task 0fec4791dba50810fe5e2dcb0b961918-init perform sendOutputFld with payload null
18:10:23.815: Executing task 0fec4791dba50810fe5e2dcb0b961918-init perform sendOutputFld with payload null
18:10:23.815 [Context] TopicName: system TopicId: 8bec4791dba50810fe5e2dcb0b961917 [TaskStateManager] Executing task 0fec4791dba50810fe5e2dcb0b961918-init perform gatherData with payload null
18:10:23.813: Executing task 0fec4791dba50810fe5e2dcb0b961918-init perform gatherData with payload null
18:10:23.813 [Context] TopicName: system TopicId: 8bec4791dba50810fe5e2dcb0b961917 [TaskStateManager] Executing task 0fec4791dba50810fe5e2dcb0b961918-init perform greet with payload null
18:10:23.812: Executing task 0fec4791dba50810fe5e2dcb0b961918-init perform greet with payload null
18:10:23.812 [Context] TopicName: system TopicId: 8bec4791dba50810fe5e2dcb0b961917 [TaskStateManager] Executing task 0fec4791dba50810fe5e2dcb0b961918-init perform init with payload null
18:10:23.810: Executing task 0fec4791dba50810fe5e2dcb0b961918-init perform init with payload null
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The issue is observed when an instance upgrades from London to Newyork Instance.

The tasks in the conversation (`sys_cs_conversation`) appear pre-NY and the System topic isn't published.

To resolve the issue follow the below steps

1. upgrade/repair the plugin com.glide.cs plugin
   2. ensure system topic is published

Note: System topic - belongs to System "Topic Categories", which is currently restricted for virtual_agent_admin role by the ACL. As per the current system design its been able to access by the "maint" role only which is the expected behaviour. Please raise the case in "HI" if you are unable to publish the system topic.

https://<instance-name>.service-now.com/sys_cb_topic_category_list.do?sysparm_query=name%3D_system_&sysparm_view=Categories
https://<instance-name>.service-now.com/sys_cs_topic_list.do?sysparm_nostack=true&sysparm_query=is_system_topic%3Dtrue&sysparm_first_row=1&sysparm_view=