I just ran into this error yesterday. What I really don't understand is that when I went into our network backup files the Thursday 5pm backup did not have the error, but the Friday 7am backup file did and the drawing was not modified between the two backups...
I will open a support case as Himanshu Gohel suggested, but if anyone figures out what is causing this please post it. Loosing 10 hours or work sucks when you are close to a deadline.
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