The test failed on branch=master, cloud=gce:
test artifacts and logs in: /home/agent/work/.go/src/github.com/cockroachdb/cockroach/artifacts/acceptance/version-upgrade/run_1
	versionupgrade.go:258,versionupgrade.go:114,versionupgrade.go:189,versionupgrade.go:177,acceptance.go:69,acceptance.go:110,test_runner.go:760: write tcp 172.17.0.3:52698->35.192.202.190:26257: write: broken pipe

	cluster.go:1637,context.go:140,cluster.go:1626,test_runner.go:841: dead node detection: /home/agent/work/.go/src/github.com/cockroachdb/cockroach/bin/roachprod monitor teamcity-2561359-1609916496-07-n4cpu4 --oneshot --ignore-empty-nodes: exit status 1 3: 5485
		4: 5484
		2: 5508
		1: dead
		Error: UNCLASSIFIED_PROBLEM: 1: dead
		(1) UNCLASSIFIED_PROBLEM
		Wraps: (2) attached stack trace
		  -- stack trace:
		  | main.glob..func14
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/pkg/cmd/roachprod/main.go:1147
		  | main.wrap.func1
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/pkg/cmd/roachprod/main.go:271
		  | github.com/spf13/cobra.(*Command).execute
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/vendor/github.com/spf13/cobra/command.go:830
		  | github.com/spf13/cobra.(*Command).ExecuteC
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/vendor/github.com/spf13/cobra/command.go:914
		  | github.com/spf13/cobra.(*Command).Execute
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/vendor/github.com/spf13/cobra/command.go:864
		  | main.main
		  | 	/home/agent/work/.go/src/github.com/cockroachdb/cockroach/pkg/cmd/roachprod/main.go:1850
		  | runtime.main
		  | 	/usr/local/go/src/runtime/proc.go:204
		  | runtime.goexit
		  | 	/usr/local/go/src/runtime/asm_amd64.s:1374
		Wraps: (3) 1: dead
		Error types: (1) errors.Unclassified (2) *withstack.withStack (3) *errutil.leafError