diff --git a/changes/2972.fix.md b/changes/2972.fix.md
new file mode 100644
index 0000000000..7444f5e7c8
--- /dev/null
+++ b/changes/2972.fix.md
@@ -0,0 +1 @@
+Handle error when convert `shmem` string value into `BinarySize`
diff --git a/src/ai/backend/manager/defs.py b/src/ai/backend/manager/defs.py
index 7c93275b18..0dc2421579 100644
--- a/src/ai/backend/manager/defs.py
+++ b/src/ai/backend/manager/defs.py
@@ -88,3 +88,5 @@ class LockID(enum.IntEnum):
 
 DEFAULT_KEYPAIR_RESOURCE_POLICY_NAME: Final = "default"
 DEFAULT_KEYPAIR_RATE_LIMIT: Final = 10000
+
+DEFAULT_SHARED_MEMORY_SIZE: Final[str] = "64m"
diff --git a/src/ai/backend/manager/registry.py b/src/ai/backend/manager/registry.py
index e1bb4679f0..e93904ea0e 100644
--- a/src/ai/backend/manager/registry.py
+++ b/src/ai/backend/manager/registry.py
@@ -132,7 +132,7 @@
     TooManySessionsMatched,
 )
 from .config import LocalConfig, SharedConfig
-from .defs import DEFAULT_IMAGE_ARCH, DEFAULT_ROLE, INTRINSIC_SLOTS
+from .defs import DEFAULT_IMAGE_ARCH, DEFAULT_ROLE, DEFAULT_SHARED_MEMORY_SIZE, INTRINSIC_SLOTS
 from .exceptions import MultiAgentError, convert_to_status_data
 from .models import (
     AGENT_RESOURCE_OCCUPYING_KERNEL_STATUSES,
@@ -1128,10 +1128,20 @@ async def enqueue_session(
             # We need to subtract the amount of shared memory from the memory limit of
             # a container, since tmpfs including /dev/shm uses host-side kernel memory
             # and cgroup's memory limit does not apply.
-            shmem = resource_opts.get("shmem", None)
-            if shmem is None:
-                shmem = labels.get("ai.backend.resource.preferred.shmem", "64m")
-            shmem = BinarySize.from_str(shmem)
+            raw_shmem: Optional[str] = resource_opts.get("shmem")
+            if raw_shmem is None:
+                raw_shmem = labels.get("ai.backend.resource.preferred.shmem")
+            if not raw_shmem:
+                # raw_shmem is None or empty string ("")
+                raw_shmem = DEFAULT_SHARED_MEMORY_SIZE
+            try:
+                shmem = BinarySize.from_str(raw_shmem)
+            except ValueError:
+                log.warning(
+                    f"Failed to convert raw `shmem({raw_shmem})` "
+                    f"to a decimal value. Fallback to default({DEFAULT_SHARED_MEMORY_SIZE})."
+                )
+                shmem = BinarySize.from_str(DEFAULT_SHARED_MEMORY_SIZE)
             resource_opts["shmem"] = shmem
             image_min_slots = copy.deepcopy(image_min_slots)
             image_min_slots["mem"] += shmem