I struggled with these errors for a while when first starting to use Tableau.
Typically, this occurred for me when something changed in relation to my extract. For instance, I revised a calculation then saved my workbook but the extract continued to reference the old calculation. If you are using an extract, go to Data>>Extract>>Remove and choose to remove and delete the extract. Then create a new extract. You may have to rebuild your calculations, but hopefully you know what they were.
Here is the KB article describing your issue:
The workbook was saved immediately after creating new calculated fields. Then the extract was refreshed, but the workbook was not saved again.
I noticed this behavior only recently (running version 8.0.5). I was able to resolve it by refreshing the extract. This morning, however, my calcs are blown resulting in a nice blank view (seen below). Surely there's a fix underway for this known behavior. And for the record, I've read the KB. My rule of thumb is always to save before exiting, especially if I've made changes.
I have always been able to get past this error by:
1) Removing and deleting the extract
2) Re-creating the extract.
This has worked for me every time. And I agree, I have received this error for no apparent reason in the past as well.
Thanks for the reply.
Obviously, always didn’t apply for me; I managed to save the error over my work last time. Let me know if you can see a way of reverting it. Otherwise, it’s back to the drawing board. For those of us with lapses in attention, this behavior could overwrite a lot of work.
How about duplicating (making a copy) of the dimension, then creating a single calculation from each of them???
Dimension 1: YYYY-MM
Dimension 2: YYYY-MM(copy)
Calc1: Date (LEFT([YYYYMM], 4)