Intermittent sandbox connection failure after Dify upgrade (1.10.1-fix.1 → 1.15.0)

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### Dify version

1.15.0

### Cloud or Self Hosted

Self Hosted (Docker)

### Steps to reproduce

I am deploying in an offline docker compose environment, when upgrading the version from dify 1.10.1-fix.1 to 1.15.0,
an error occurred, please guide me on how to resolve this?

Dify will appear in version 1.10, but the probability of its occurrence is very low, approximately 10%. The probability of Dify appearing in version 1.15 is around 50%

error info:

```
sandbox-1 | INFO: 192.168.64.11:35966 - "POST /v1/sandbox/run HTTP/1.1" 200 OK
worker-1 | 2026-07-06 07:44:55.989 INFO [GraphWorker-1] [_client.py:1025] 69edaaac7b335c3ba4ff38c3a86011c0 - HTTP Request: POST http://sandbox:8194/v1/sandbox/run "HTTP/1.1 200 OK"
worker-1 | 2026-07-06 07:44:56.129 ERROR [GraphDispatcher] [error_handler.py:104] - Node 1782289548987 failed with ABORT strategy: Failed to execute code, which is likely a network issue, please check if the sandbox service is running. ( Error: Server disconnected without sending a response. )
worker-1 | 2026-07-06 07:44:56.348 ERROR [Thread-129 (_generate_worker)] [workflow_entry.py:248] 69edaaac7b335c3ba4ff38c3a86011c0 - Unknown Error when workflow entry running
worker-1 | Traceback (most recent call last):
worker-1 | File "/app/api/core/workflow/workflow_entry.py", line 244, in run
worker-1 | yield from generator
worker-1 | File "/app/api/core/workflow/workflow_entry.py", line 57, in iter_dify_graph_engine_events
worker-1 | yield from filter_graph_events(
worker-1 | File "/app/api/.venv/lib/python3.12/site-packages/graphon/graph_engine/filters/chain.py", line 21, in filter_graph_events
worker-1 | for event in events:
worker-1 | ^^^^^^
worker-1 | File "/app/api/.venv/lib/python3.12/site-packages/graphon/graph_engine/graph_engine.py", line 309, in run
worker-1 | yield from lifecycle.run()
worker-1 | File "/app/api/.venv/lib/python3.12/site-packages/graphon/graph_engine/graph_engine.py", line 77, in run
worker-1 | yield from self.emit_terminal_events()
worker-1 | File "/app/api/.venv/lib/python3.12/site-packages/graphon/graph_engine/graph_engine.py", line 341, in _emit_terminal_events
worker-1 | raise error
worker-1 | RuntimeError: Failed to execute code, which is likely a network issue, please check if the sandbox service is running. ( Error: Server disconnected without sending a response. )
worker-1 | 2026-07-06 07:44:56.354 ERROR [GraphDispatcher] [error_handler.py:104] - Node 1778722729299 failed with ABORT strategy: Failed to invoke tool [网络组件]通知模板: Failed to execute code, which is likely a network issue, please check if the sandbox service is running. ( Error: Server disconnected without sending a response. )
nginx-1 | 10.xx.1xx.1x1 - - [06/Jul/2026:07:44:56 +0000] "POST /console/api/apps/98d26167-9ac8-4f05-944e-0aea2d905224/advanced-chat/workflows/draft/run HTTP/1.1" 200 122575 "http://10.231.147.37/app/98d26167-9ac8-4f05-944e-0aea2d905224/workflow" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/149.0.0.0 Safari/537.36" "-"
worker-1 | 2026-07-06 07:44:56.524 INFO [Dummy-118] [trace.py:128] 69edaaac7b335c3ba4ff38c3a86011c0 - Task tasks.app_generate.workflow_execute_task.workflow_based_app_execution_task[03c466e7-a725-4bd8-9695-349fe3521ea8] succeeded in 330.21767717879266s: None
worker-1 | 2026-07-06 07:44:58.527 ERROR [Thread-119 (_generate_worker)] [workflow_entry.py:248] 69edaaac7b335c3ba4ff38c3a86011c0 - Unknown Error when workflow entry running
worker-1 | Traceback (most recent call last):
worker-1 | File "/app/api/core/workflow/workflow_entry.py", line 244, in run
worker-1 | yield from generator
worker-1 | File "/app/api/core/workflow/workflow_entry.py", line 57, in iter_dify_graph_engine_events
worker-1 | yield from filter_graph_events(
worker-1 | File "/app/api/.venv/lib/python3.12/site-packages/graphon/graph_engine/filters/chain.py", line 21, in filter_graph_events
worker-1 | for event in events:
worker-1 | ^^^^^^
worker-1 | File "/app/api/.venv/lib/python3.12/site-packages/graphon/graph_engine/graph_engine.py", line 309, in run
worker-1 | yield from lifecycle.run()
worker-1 | File "/app/api/.venv/lib/python3.12/site-packages/graphon/graph_engine/graph_engine.py", line 77, in run
worker-1 | yield from self.emit_terminal_events()
worker-1 | File "/app/api/.venv/lib/python3.12/site-packages/graphon/graph_engine/graph_engine.py", line 341, in _emit_terminal_events
worker-1 | raise error
worker-1 | RuntimeError: Failed to invoke tool [网络组件]通知模板: Failed to execute code, which is likely a network issue, please check if the sandbox service is running. ( Error: Server disconnected without sending a response. )
nginx-1 | 10.xx.1xx.1x1 - - [06/Jul/2026:07:44:59 +0000] "GET /console/api/apps/98d26167-9ac8-4f05-944e-0aea2d905224/workflows/draft/system-variables HTTP/1.1" 200 13 "http://10.231.147.37/app/98d26167-9ac8-4f05-944e-0aea2d905224/workflow" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/149.0.0.0 Safari/537.36
```

### ✔️ Expected Behavior

Expectations should be running normally

### ❌ Actual Behavior

_No response_

Start by reproducing the intermittent failure in the offline Docker Compose deployment while comparing versions 1.10.1-fix.1 and 1.15.0. Read api/core/workflow/workflow_entry.py and inspect the worker and sandbox logs around POST /v1/sandbox/run; done means workflow code execution completes reliably without the disconnection error.

Written by the indexing model from the issue text.