I did try along the similar lines first, but I could see the CI in the cmdb, so it is a valid CI

What else can cause it ?

I tried this and it exactly gave me the same error. Tried to update the change task with a CI that did not meet the reference qualifier conditions. 

Check if the CI you are trying to update meets the qualifier conditions for CI field on change task table or parent(task) table

HI Harshiya,

Sorry I didnt get what you wanted me to check. This record is on the change task.

Thanks,

so,

1. Go to change task form

2. right click on configuration item field and choose configure dictionary

3. check reference specification section

4. check if the ci you are  wanting to update is meeting the criteria in the reference qualifier section. If you dont find any check in task which is the parent table for change task.  Like in the snapshot above i dont have any additional filters to filter the data i can select on the change form. 

 https://docs.servicenow.com/bundle/london-platform-administration/page/script/server-scripting/conce...

Also, post a screenshot of what is configured at your end

Hello,

Yes, the CI i m trying to select matches the filter condition and also the ci field is on task table