Hi, @Richa Kumari
Thank you for posting in Microsoft Q&A forum.
It turns out that there was some changed made to the Install Software Update step and it causes the Import Wizard to fail.
You may remove the Install Software Update step before exporting your Task Sequence.
Or you may try to delete the "SMS_TaskSequence_InstallUpdateAction" Step(s) from the object.xml inside the Task Sequence ZIP like below blog mentioned:
https://miketerrill.net/2016/07/31/import-task-sequence-failure-cm-1606/
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