You have a file where Cell5 does not occur in the name, so skip that one
Put this right after the for, as the first thing in the loop
if ~contains(Textfiles(i,:), 'Cell5', 'IgnoreCase', true)
continue; % Skip this file.
end
Alternatively, or perhaps even better since it does not depend on any particular string leteral being in the name, you could do
if ~isequal(oldfilename, oldfilename)
% Only rename if the filenames are different.
movefile(oldfilename, newfilename);
end
