What version of Go are you using (go version)?

Using tip:

$ go version
go version devel go1.22-90276c268b Tue Oct 3 18:06:38 2023 +0000 linux/amd64

Does this issue reproduce with the latest release?

No, only with tip.

What operating system and processor architecture are you using (go env)?

linux/amd64

What did you do?

For this set of packages:

https://go.dev/play/p/5nloPBjspW9?v=gotip

run

$ go test -coverprofile=foo.p ./...
...
$ go tool cover -html=foo.p

What did you expect to see?

No error from go tool -cover.

What did you see instead?

$ go test -coverprofile=foo.p ./...
?   	M/n	[no test files]
	M/xinternal/q		coverage: 0.0% of statements
	M/it		coverage: 0.0% of statements
	M/x		coverage: 0.0% of statements
	M/xinternal		coverage: 0.0% of statements
ok  	M/a	0.022s	coverage: 100.0% of statements
ok  	M/aa	0.020s	coverage: 77.8% of statements
ok  	M/b	0.021s	coverage: 100.0% of statements
ok  	M/deadstuff	0.019s	coverage: 33.3% of statements
ok  	M/main	0.018s	coverage: 75.0% of statements
ok  	M/onlytest	0.018s	coverage: [no statements]
$ go tool cover -html=foo.p
cover: can't read "t.go": open /tmp/covex/t.go: no such file or directory
$

What's happening here is that the cover profile fragments generated for the no-test packages are being written to a temporary coverage profile that has an unqualified path, meaning that if multiple test runs are happening in parallel we'll get a collision (this is what happens with foo.p above).