This error is returned when you are attempting to update a metric that currently contains locked values. In the instance that you are attempting to adjust a period that has already actualized (in whole or in part), you will need to "Unlock past data" to make adjustments.

If the month you are attempting to adjust has only partially actualized, you can also adjust Time Groups to include weeks - all actualized weeks will be displayed in dark gray.
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You can read more about unlocking past data here.

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