NSX-V 6.4.10 (and earlier versions) Plugin not loading on vCenter Server 7.0 U3 with error (HTTP Status 500 – Internal Server Error)

Products

• VMware NSX
• VMware vCenter Server

Issue/Introduction

Symptoms:

• On All NSX-V 6.4.10 (or lower versions) Plugin pages error is displayed: “HTTP Status 500 – Internal Server Error”
• You may see the similar entries in /var/log/vmware/vsphere-ui/logs/vsphere_client_virgo.log

[2021-06-14T08:46:33.590Z] [WARN ] http-nio-5090-exec-38 o.s.w.s.mvc.method.annotation.ExceptionHandlerExceptionResolver Failure in @ExceptionHandler com.vmware.nsxv.html.mvc.controller.NGCManagementController#exceptionHandler(Exception) java.lang.NoSuchMethodError: org.springframework.http.MediaType.getCharSet()Ljava/nio/charset/Charset;
        at com.vmware.nsxv.html.json.mapper.NsxH5HttpMessageConverter.getJsonEncoding(NsxH5HttpMessageConverter.java:139)
        at com.vmware.nsxv.html.json.mapper.NsxH5HttpMessageConverter.writeInternal(NsxH5HttpMessageConverter.java:96)
        at org.springframework.http.converter.AbstractHttpMessageConverter.write(AbstractHttpMessageConverter.java:227)

Environment

VMware vCenter Server 7.0.3

Resolution

This issue is resolved in NSX-V 6.4.11. For more information, see VMware NSX Data Center for vSphere 6.4.11 Release Notes

Workaround:
Once vCenter Server is upgraded to 7.0 U3 or higher version while NSX-V is still 6.4.10 or lower version , Spring (one of the vSphere-UI components) version of vCenter needs to be downgraded so that it can interact with Plugins having older Spring version.

To downgrade vCenter Server Spring version, please follow these steps:

1. Login to vCenter Server Appliance (VCSA) through SSH using Putty (using root account)
2. Navigate to /etc/vmware/vmware-vmon/svcCfgfiles/ as below:

# cd /etc/vmware/vmware-vmon/svcCfgfiles/

3. Backup the vsphere-ui.json using the below command:

# cp vsphere-ui.json vsphere-ui.json.bak

4. Edit the file vsphere-ui.json using text editor.

# vi vsphere-ui.json 

5. Search for the value //“-DuseOldSpring=true" 
6. Enter the letter i to enter Insert mode.
7. Delete the // 

Value after changes should look like “-DuseOldSpring=true"

8. Press ESC key to exit the Insert mode.
9. Press :wq! to save changes and exit.
10. Restart vsphere-ui service using the below commands:

# service-control --stop vsphere-ui
# service-control --start vsphere-ui