diff --git a/src/cmd/go/internal/modload/init.go b/src/cmd/go/internal/modload/init.go
index b9d9d2e5527..f4f4a68254b 100644
--- a/src/cmd/go/internal/modload/init.go
+++ b/src/cmd/go/internal/modload/init.go
@@ -485,7 +485,13 @@ func Init() {
 	if len(list) > 0 && list[0] != "" {
 		gopath = list[0]
 		if _, err := fsys.Stat(filepath.Join(gopath, "go.mod")); err == nil {
-			base.Fatalf("$GOPATH/go.mod exists but should not")
+			fmt.Fprintf(os.Stderr, "go: warning: ignoring go.mod in $GOPATH %v\n", gopath)
+			if RootMode == NeedRoot {
+				base.Fatal(ErrNoModRoot)
+			}
+			if !mustUseModules {
+				return
+			}
 		}
 	}
 }
diff --git a/src/cmd/go/testdata/script/env_issue46807.txt b/src/cmd/go/testdata/script/env_issue46807.txt
new file mode 100644
index 00000000000..e37bc63e6c9
--- /dev/null
+++ b/src/cmd/go/testdata/script/env_issue46807.txt
@@ -0,0 +1,12 @@
+! go mod tidy
+stderr '^go: warning: ignoring go.mod in \$GOPATH'
+stderr '^go: go.mod file not found in current directory or any parent directory; see ''go help modules'''
+
+go env
+stdout 'GOPATH='
+stderr '^go: warning: ignoring go.mod in \$GOPATH'
+
+-- $GOPATH/go.mod --
+module bug
+
+go 1.21
\ No newline at end of file