readtable has stopped working on xlsx files

I am running 2024a Matlab on a Windows PC. I have code that loads an existing sheet of an xlsx file. It was working at the beginning of March. I switched my personal Matlab library from dropbox to github (only change I'm aware of; no change to Matlab directories) and now I get the following error message:

T = readtable(filename, 'Sheet', 'sheet name');

Error using readtable (line 517)

Conversion to cell from char is not possible.

This error also occurs if I try:

opts = detectImportOptions(filename, 'Sheet', 'sheet name');

Error using detectImportOptions (line 428)

Conversion to cell from char is not possible.

I've tried this on 2 Windows machines. One was recently updated to Windows 11, the other is still running Windows 10.

What could have happened?

btw, if I type which -all readtable, I get the following on both machines:

C:\Program Files\MATLAB\R2024a\toolbox\matlab\iofun\readtable.m

C:\Program Files\MATLAB\R2024a\toolbox\shared\io\general\+matlab\+io\@ImportOptions\ImportOptions.m % matlab.io.ImportOptions method

Answer 1

[Walter Roberson]

The most common cause of these sorts of problems, is if you have a third-party .m file that is interfering with a MATLAB function. For example if you had a height.m or width.m then those sorts of problems can occur.

Experiment with

restoredefaultpath; rehash toolboxcache

(If the functions still do not work, there is the possibility that the interfering function is in your current working directory.)

[Karen]

Thanks! Restoring the default path worked and, by successively adding directories, I narrowed it down to one but it's still not clear which mfile in that directory is causing the problem (they seem totally unrelated in both name and function). I did note that matlab.io.internal.legacyReadtable does work, even if when the problem directory is in my path. For future investigations.