Workflow error: Unable to retrive value for Task as service responded with the error begin 5, end 4,

Summary:

Hello,

We have configured workflow in advanced mode. Unfortunately in some cases it return error which doesn't explain to much. When you look at screenshot, into section Values, for task we have error:

Unable to retrive value for Task as service responded with the error begin 5, end 4, length 4

Does any one knows, what does it mean?

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