diff --git a/sbin/bectl/bectl.c b/sbin/bectl/bectl.c
--- a/sbin/bectl/bectl.c
+++ b/sbin/bectl/bectl.c
@@ -233,7 +233,10 @@
 	bootenv = *argv;
 
 	err = BE_ERR_SUCCESS;
-	if ((atpos = strchr(bootenv, '@')) != NULL) {
+	if (strchr(bootenv, ' ') != NULL)
+		/* BE datasets with spaces are not bootable */
+		err = BE_ERR_INVALIDNAME;
+	else if ((atpos = strchr(bootenv, '@')) != NULL) {
 		/*
 		 * This is the "create a snapshot variant". No new boot
 		 * environment is to be created here.
@@ -261,6 +264,10 @@
 	switch (err) {
 	case BE_ERR_SUCCESS:
 		break;
+	case BE_ERR_INVALIDNAME:
+		fprintf(stderr,
+		    "bectl create: boot environment name must not contain spaces\n");
+		break;
 	default:
 		if (atpos != NULL)
 			fprintf(stderr,
diff --git a/sbin/bectl/tests/bectl_test.sh b/sbin/bectl/tests/bectl_test.sh
--- a/sbin/bectl/tests/bectl_test.sh
+++ b/sbin/bectl/tests/bectl_test.sh
@@ -122,6 +122,10 @@
 	atf_check zfs create -o mountpoint=/usr -o canmount=noauto \
 	    ${zpool}/ROOT/default/usr
 
+	# BE datasets with spaces are not bootable, PR 254441.
+	atf_check -e not-empty -s not-exit:0 \
+		bectl -r ${zpool}/ROOT create "foo bar"
+
 	# Test standard creation, creation of a snapshot, and creation from a
 	# snapshot.
 	atf_check bectl -r ${zpool}/ROOT create -e default default2