diff --git a/.unreleased/pr_9717 b/.unreleased/pr_9717
new file mode 100644
index 00000000000..95484349fd2
--- /dev/null
+++ b/.unreleased/pr_9717
@@ -0,0 +1 @@
+Fixes: #9717 Reject non-positive time bucket width on cagg creation
diff --git a/tsl/src/continuous_aggs/common.c b/tsl/src/continuous_aggs/common.c
index 3519e9ea3ac..b6d4da5b24b 100644
--- a/tsl/src/continuous_aggs/common.c
+++ b/tsl/src/continuous_aggs/common.c
@@ -435,6 +435,13 @@ process_timebucket_parameters(FuncExpr *fe, ContinuousAggBucketFunction *bf, boo
 	bf->bucket_function = fe->funcid;
 	bf->bucket_time_based = ts_continuous_agg_bucket_on_interval(bf->bucket_function);
 	bf->bucket_fixed_interval = time_bucket_info_has_fixed_width(bf);
+
+	if (process_checks && is_cagg_create && ts_continuous_agg_bucket_width(bf) <= 0)
+	{
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("time bucket width must be greater than zero")));
+	}
 }
 
 /*
diff --git a/tsl/test/expected/cagg_errors.out b/tsl/test/expected/cagg_errors.out
index 7ac658d016d..4a7dba32488 100644
--- a/tsl/test/expected/cagg_errors.out
+++ b/tsl/test/expected/cagg_errors.out
@@ -230,6 +230,29 @@ FROM conditions
 GROUP BY 1
 WITH NO DATA;
 ERROR:  invalid bucket width for time bucket function
+-- negative or zero bucket width must be rejected at creation time;
+-- otherwise refresh later trips Assert(bucket_width > 0).
+CREATE MATERIALIZED VIEW mat_neg WITH (timescaledb.continuous)
+AS
+SELECT time_bucket('-1 hour'::interval, timec), avg(temperature)
+FROM conditions
+GROUP BY 1
+WITH NO DATA;
+ERROR:  time bucket width must be greater than zero
+CREATE MATERIALIZED VIEW mat_zero WITH (timescaledb.continuous)
+AS
+SELECT time_bucket('0'::interval, timec), avg(temperature)
+FROM conditions
+GROUP BY 1
+WITH NO DATA;
+ERROR:  time bucket width must be greater than zero
+CREATE MATERIALIZED VIEW mat_neg_month WITH (timescaledb.continuous)
+AS
+SELECT time_bucket('-1 month'::interval, timec), avg(temperature)
+FROM conditions
+GROUP BY 1
+WITH NO DATA;
+ERROR:  time bucket width must be greater than zero
 -- row security on table
 create table rowsec_tab( a bigint, b integer, c integer);
 select table_name from create_hypertable( 'rowsec_tab', 'a', chunk_time_interval=>10);
@@ -594,3 +617,30 @@ ERROR:  invalid continuous aggregate view
 -- No FROM clause in CAGG definition
 CREATE MATERIALIZED VIEW cagg1 with (timescaledb.continuous, timescaledb.materialized_only=false) AS SELECT 1 GROUP BY 1 WITH NO DATA;
 ERROR:  invalid continuous aggregate query
+-- non-positive bucket width on integer-typed hypertable
+CREATE TABLE int_ht(timec bigint NOT NULL, val float);
+SELECT create_hypertable('int_ht', 'timec', chunk_time_interval => 1000000);
+  create_hypertable   
+----------------------
+ (19,public,int_ht,t)
+
+CREATE OR REPLACE FUNCTION int_ht_now() RETURNS bigint LANGUAGE SQL STABLE AS $$ SELECT 0::bigint $$;
+SELECT set_integer_now_func('int_ht', 'int_ht_now');
+ set_integer_now_func 
+----------------------
+ 
+
+CREATE MATERIALIZED VIEW mat_neg_int WITH (timescaledb.continuous)
+AS
+SELECT time_bucket(-100::bigint, timec), avg(val)
+FROM int_ht
+GROUP BY 1
+WITH NO DATA;
+ERROR:  time bucket width must be greater than zero
+CREATE MATERIALIZED VIEW mat_zero_int WITH (timescaledb.continuous)
+AS
+SELECT time_bucket(0::bigint, timec), avg(val)
+FROM int_ht
+GROUP BY 1
+WITH NO DATA;
+ERROR:  time bucket width must be greater than zero
diff --git a/tsl/test/sql/cagg_errors.sql b/tsl/test/sql/cagg_errors.sql
index 61e5b2cccd0..7f75dc1bce8 100644
--- a/tsl/test/sql/cagg_errors.sql
+++ b/tsl/test/sql/cagg_errors.sql
@@ -209,6 +209,29 @@ FROM conditions
 GROUP BY 1
 WITH NO DATA;
 
+-- negative or zero bucket width must be rejected at creation time;
+-- otherwise refresh later trips Assert(bucket_width > 0).
+CREATE MATERIALIZED VIEW mat_neg WITH (timescaledb.continuous)
+AS
+SELECT time_bucket('-1 hour'::interval, timec), avg(temperature)
+FROM conditions
+GROUP BY 1
+WITH NO DATA;
+
+CREATE MATERIALIZED VIEW mat_zero WITH (timescaledb.continuous)
+AS
+SELECT time_bucket('0'::interval, timec), avg(temperature)
+FROM conditions
+GROUP BY 1
+WITH NO DATA;
+
+CREATE MATERIALIZED VIEW mat_neg_month WITH (timescaledb.continuous)
+AS
+SELECT time_bucket('-1 month'::interval, timec), avg(temperature)
+FROM conditions
+GROUP BY 1
+WITH NO DATA;
+
 -- row security on table
 create table rowsec_tab( a bigint, b integer, c integer);
 select table_name from create_hypertable( 'rowsec_tab', 'a', chunk_time_interval=>10);
@@ -504,3 +527,23 @@ CREATE MATERIALIZED VIEW cagg1 WITH (timescaledb.continuous, timescaledb.materia
 
 -- No FROM clause in CAGG definition
 CREATE MATERIALIZED VIEW cagg1 with (timescaledb.continuous, timescaledb.materialized_only=false) AS SELECT 1 GROUP BY 1 WITH NO DATA;
+
+-- non-positive bucket width on integer-typed hypertable
+CREATE TABLE int_ht(timec bigint NOT NULL, val float);
+SELECT create_hypertable('int_ht', 'timec', chunk_time_interval => 1000000);
+CREATE OR REPLACE FUNCTION int_ht_now() RETURNS bigint LANGUAGE SQL STABLE AS $$ SELECT 0::bigint $$;
+SELECT set_integer_now_func('int_ht', 'int_ht_now');
+
+CREATE MATERIALIZED VIEW mat_neg_int WITH (timescaledb.continuous)
+AS
+SELECT time_bucket(-100::bigint, timec), avg(val)
+FROM int_ht
+GROUP BY 1
+WITH NO DATA;
+
+CREATE MATERIALIZED VIEW mat_zero_int WITH (timescaledb.continuous)
+AS
+SELECT time_bucket(0::bigint, timec), avg(val)
+FROM int_ht
+GROUP BY 1
+WITH NO DATA;