I have changed Office 2003 to Office 2021 and thus also Excel in the same way. The conversion is mostly good and Excel 2021 nicely converts the xls files to xlsx files.
But I'm having problems with some charts when I try to expand the contents of a series.
When I right-click on a series in one chart and select Select Data... the Select Data Source window normally opens and the Chart Data Range it already filled in, e.g. ='2020'!$B$281:$B$985;'2020'!$R$281:$R$985. The first part is then the Date column (which belongs on the x-axis) and the second part is the Value column (which is on the y-axis).
When I right click on a series in another chart there is nothing filled in for Chart data range, instead it says "Data range is too complex to display". If I then click on Edit for the series in question, there stands only ='2020'!$O$29:$O$985, namely the data for Value.
The only difference between the two charts is that the first shows only 1 series, while the second shows 7. Can anyone explain for me what the error is and what I can do about it.
Now I know what is wrong when Excel thinks "the data range is too complex to display". Then, when marking the columns to be included in the diagram, you have accidentally marked one cell too much in one column compared to the others. (A blank one at the beginning or at the end). Clearly, the data area can then be perceived as "complex". /hans peter