Return unique values across multiple sheets

Question

On a Google spreadsheet I have multiple sheets that are named by month. Each sheet has a section where it gets all unique values in a range by using =UNIQUE(the_range) which is what I want.

I want to create a summary sheet which then pulls all the unique values from all the sheet within a defined range. Currently I've tried this:

=UNIQUE({'01 July - 12 July 2021'!G10:G22,'June 2021'!G10:G22,'May 2021'!G11:G19,'April 2021'!G10:G20}, false, false)

The error returned is: Function array_row parameter 3 has mismatched row size

Can anyone help me find a better way to return these unique values across multiple sheets?

Answer 1

Instead of

{'01 July - 12 July 2021'!G10:G22,'June 2021'!G10:G22,'May 2021'!G11:G19,'April 2021'!G10:G20}

use

'01 July - 12 July 2021'!G10:G22; 'June 2021'!G10:G22; 'May 2021'!G11:G19;'April 2021'!G10:G20}

The fist array returns an error because the ranges hasn't the same number of rows (two has 22, one has 18 and other has 20). The second array will not return an error because as all the ranges has one column; the rows will be stacked.