grep -Pozl "(?s)The message can't be displayed on one line.*Please see this part of the message on the next line"
This is a Perl-style regex that searches for different parts of expression that are scattered among several lines; it then prints the files where it finds these occurences; it does not print the line number as it would be line #1 in all cases due to the fact that we turn newlines into null characters here. It it though needed to manually place .* between what you think may be delimited by newline or some auxillary text in the original file.
P - perl regex; (?s) - enables .* to match anything - literally anything; o - output matching piece of line only (otherwise you will see the whole file as output); z - make grep think that the input is just one single big line (not perl-specific, it can be used with usual or extended regex too); l - print the file names where a match is found;