Really?
https://travel.gc.ca/returning/customs/entering-canada
Permanent residents
Permanent residents (immigrants living in Canada who are not yet Canadian citizens) need a valid permanent resident card to return to Canada. Check the expiry date on your card.
Note that a Certificate of Canadian Citizenship is not a travel document. See
Canadian Citizenship for further details.
Please, how many times must we revisit exaclty the same topic?
Yes, government
recommends and says in pretty strong language that PRs should travel with a PR card.
They will never, ever suggest it is a good idea to travel without one.
But they also
cannot deny that a PR who makes it to a land border (i.e. not travelling by commercial carrier) will
not be denied entry if they can show they are a PR. (Citizens too but different issue obviously). An expired PR card is sufficient to do so. So is almost any valid ID that matches properly the name DOB etc that they have on file. They
must let a PR enter - the only difficulty can be demonstrating that they are that PR in their files. (Caveat for if all computers are down).
They can still make it unpleasant (secondary, wait a few hours, mild haranguing for travelling without proper id, etc) IF they want to.
Let's please not go over this again. This is a settled matter. IMO.