What will be the impact on production users\authentication etc..if FRS to DFSr sysvol Migration will get failed in any of stage 1,2,3..

I am planning to migrate sysvol FRS to DFSr  directly in production, could you pls share what could be worse impact if migration gets stucked on any stage eg. 1, 2, 3 (Prepared, redirected, eliminated).

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Nitin