"Error posting changes" when updating integer column in data-grid (4332331)

When updating an integer column in the data-grid and getting an "Error posting changes":

"Index and length must refer to a location within the string.
Parameter name: length
Do you want to keep your changes so can edit them?

Clicking on Yes in the dialogue causes the following exception

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Exception Information
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Exception: System.ArgumentOutOfRangeException
Message : Index and length must refer to a location within the string.
Parameter name: length
Stack Trace:
at Quest.Toad.Grid.ToadGridControl.persistChanges(Object dataSource,Boolean allowBack)