Cannot sort table in libreoffice

I’ve been using libreoffice for several years and suddenly I cannot sort a table created in a libreoffice document. When I attempt to effect a sort operation, I receive cannot sort selection error message. I select the entire document with select all command and sort in ascending order by rows. I’ve attempted to isolate the problem in the table by selecting different parts of the table thinking there is something wrong with a cell. This technique proved to be inconclusive since sometimes I received the error when sorting parts of the table and sometimes I didn’t. I’ve tried copying the entire document into a new document, but same error occurs.

Which OS and LO_Version do you use?

If you want to sort the table, you must also mark the table and not the document.

I have sorted this table many times without receiving this error: cannot sort selection
All my successful and currently unsuccessful sorts were done with the appropriate cells/rows/columns marked by selecting the top row of cells and then choosing the Select All under the File Menu. This operation always marks the entire table currently and in the past. I’m sure there’s a user error on my side, but I haven’t recently done anything recently related to the table except to add some additional rows. The table is about 45 pages. Thinking I was selecting something outside the table between cells, I checked for open spaces between the cell rows and there were none.

ron

Added additional information about my table sorting problem with solution found below dtd 10/23/2019:
I found my problem by sorting blocks of the table until I found the row that was preventing me from sorting the table. It turns out that I had inadvertently split a cell in one row making this row of cells have three columns instead of the two columns found in all other rows of the table.