diff --git a/api/core/sandbox/builder.py b/api/core/sandbox/builder.py
index 6ec2bd38aa..efb7e88c9b 100644
--- a/api/core/sandbox/builder.py
+++ b/api/core/sandbox/builder.py
@@ -175,11 +175,11 @@ class SandboxBuilder:
 
                     if sandbox.is_cancelled():
                         return
-                    # Storage mount is part of readiness. If restore/mount fails,
-                    # the sandbox must surface initialization failure instead of
-                    # becoming "ready" with missing files.
-                    if not sandbox.mount():
-                        raise RuntimeError("Sandbox storage mount failed")
+                    # Attempt to restore prior workspace state.  mount() returns
+                    # False when no archive exists yet (first run for this
+                    # sandbox_id), which is a normal case — not an error.
+                    # Actual failures (download/extract) surface as exceptions.
+                    sandbox.mount()
                     sandbox.mark_ready()
             except Exception as exc:
                 try:
diff --git a/api/core/sandbox/storage/archive_storage.py b/api/core/sandbox/storage/archive_storage.py
index bdc8e2021b..2f6c436cad 100644
--- a/api/core/sandbox/storage/archive_storage.py
+++ b/api/core/sandbox/storage/archive_storage.py
@@ -4,7 +4,6 @@ from __future__ import annotations
 
 import logging
 
-from core.virtual_environment.__base.exec import PipelineExecutionError
 from core.virtual_environment.__base.helpers import pipeline
 from core.virtual_environment.__base.virtual_environment import VirtualEnvironment
 from extensions.storage.base_storage import BaseStorage
@@ -47,19 +46,15 @@ class ArchiveSandboxStorage(SandboxStorage):
         download_url = self._storage.get_download_url(self._storage_key, _ARCHIVE_TIMEOUT)
         archive = "archive.tar.gz"
 
-        try:
-            (
-                pipeline(sandbox)
-                .add(["curl", "-fsSL", download_url, "-o", archive], error_message="Failed to download archive")
-                .add(
-                    ["sh", "-c", 'tar -xzf "$1" 2>/dev/null; exit $?', "sh", archive], error_message="Failed to extract"
-                )
-                .add(["rm", archive], error_message="Failed to cleanup")
-                .execute(timeout=_ARCHIVE_TIMEOUT, raise_on_error=True)
+        (
+            pipeline(sandbox)
+            .add(["curl", "-fsSL", download_url, "-o", archive], error_message="Failed to download archive")
+            .add(
+                ["sh", "-c", 'tar -xzf "$1" 2>/dev/null; exit $?', "sh", archive], error_message="Failed to extract"
             )
-        except PipelineExecutionError:
-            logger.exception("Failed to mount archive for sandbox %s", self._sandbox_id)
-            return False
+            .add(["rm", archive], error_message="Failed to cleanup")
+            .execute(timeout=_ARCHIVE_TIMEOUT, raise_on_error=True)
+        )
 
         logger.info("Mounted archive for sandbox %s", self._sandbox_id)
         return True