The error occurs if the fpsallformats module is not added.
lazarus / 49-FPSpreadsheet

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dvigor · 2022-02-03 08:00

The error occurs if the fpsallformats module is not added. The
application compiles and runs.

Maybe someone else will look for the cause ...

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PascalDragon · 2022-02-03 08:08

FPSpreadsheet itself doesn't contain the readers/writers for the
document formats, they are contained in separate units. Thus you need
to either use them separately (in case of xlsx it's xlsxooxml) or you
can use fpsallformats which simply registers all formats that
FPSpreadsheet supports. This is by design and not an error.

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dvigor · 2022-02-03 11:18

Thanks, for some reason the module was spontaneously removed from the
list uses. For a long time I could not find the reason for this
behavior.

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wp · 2022-02-03 12:15

Maybe you did it yourself and were not aware of its consequences.

The IDE highlights this unit and classifies it as "unused". In fact,
it does not contain any code and thus there is nothing which can be
called from your project. That's true. But it is not "useless". It
adds all fpspreadsheet reader/writer units to its uses clause, and
this has the effect that their initialization code is executed and
registers the reader/writer classes in your project.

The IDE hint about "unused" units, however, is correct in most of the
cases nevertheless. For example when you added a component to a form
but later deleted the component again. In this case the unit of the
component remains in the uses clause and really becomes "unused".

So think twice when you remove an "unused" unit.

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dvigor · 2022-02-04 07:51

Thank you. You are absolutely right.