B2 CLI Hanging and Not Completing #1118
Description
We have a report from a customer that the b2 sync command is hanging and not completing. This is causing lots of issues with the user's ability to keep their project websites updated.
This is the current error they are seeing:
This is the current error I am seeing, literally occurred just now (5ish minutes ago). A couple of files uploaded, and then this error. As mentioned above, the “pause” keeps incrementing, but it just increments and increments and never resolves — seemingly hung forever.
b2sdk._internal.exception.ServiceError: 503 service_unavailable vault cannot start new uploads
INFO:b2sdk._internal.b2http:Pausing thread for 17 seconds because that is what the default exponential backoff is
DEBUG:urllib3.connectionpool:Resetting dropped connection: [pod-000-1133-02.backblaze.com](http://pod-000-1133-02.backblaze.com/)
They were able to get debug logs:
DEBUG:b2sdk._internal.exception:calling interpret_b2_error(status=503, code='service_unavailable', message='vault cannot start new uploads', response_headers={'Server': 'nginx', 'Date': 'Tue, 07 Oct 2025 18:06:11 GMT', 'Content-Type': 'application/json;charset=utf-8', 'Content-Length': '99', 'Connection': 'keep-alive', 'Cache-Control': 'max-age=0, no-cache, no-store', 'Strict-Transport-Security': 'max-age=63072000'}, post_params=None)
DEBUG:b2sdk._internal.b2http:503 service_unavailable vault cannot start new uploads
Traceback (most recent call last):
File "/opt/homebrew/Cellar/b2-tools/4.4.2/libexec/lib/python3.13/site-packages/b2sdk/_internal/b2http.py", line 597, in _translate_and_retry
return cls._translate_errors(fcn, post_params)
~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
File "/opt/homebrew/Cellar/b2-tools/4.4.2/libexec/lib/python3.13/site-packages/b2sdk/_internal/b2http.py", line 525, in _translate_errors
raise interpret_b2_error(
...<5 lines>...
)
b2sdk._internal.exception.ServiceError: 503 service_unavailable vault cannot start new uploads
INFO:b2sdk._internal.b2http:Pausing thread for 3 seconds because that is what the default exponential backoff is
DEBUG:urllib3.connectionpool:Resetting dropped connection: [pod-000-1121-05.backblaze.com](http://pod-000-1121-05.backblaze.com/)
DEBUG:urllib3.connectionpool:[https://pod-000-1162-08.backblaze.com:443](https://pod-000-1162-08.backblaze.com/) "POST /b2api/v4/b2_upload_file/21e799824398e2af83430a16/c002_v0001162_t0059 HTTP/1.1" 200 780
DEBUG:b2sdk._internal.account_info.upload_url_pool:calling UrlPoolAccountInfo.put_bucket_upload_url(self=<b2sdk._internal.account_info.sqlite_account_info.SqliteAccountInfo object at 0x103d1c980>, bucket_id='21e799824398e2af83430a16') (hidden args: upload_url, upload_auth_token)
upload
DEBUG:urllib3.connectionpool:[https://pod-000-1121-05.backblaze.com:443](https://pod-000-1121-05.backblaze.com/) "POST /b2api/v4/b2_upload_file/" 503 106
DEBUG:b2sdk._internal.exception:calling interpret_b2_error(status=503, code='service_unavailable', message='connection interrupted, retry request', response_headers={'Server': 'nginx', 'Date': 'Tue, 07 Oct 2025 18:06:12 GMT', 'Content-Type': 'application/json;charset=utf-8', 'Content-Length': '106', 'Connection': 'keep-alive', 'Cache-Control': 'max-age=0, no-cache, no-store', 'Strict-Transport-Security': 'max-age=63072000'}, post_params=None)
DEBUG:b2sdk._internal.b2http:503 service_unavailable connection interrupted, retry request
Traceback (most recent call last):
File "/opt/homebrew/Cellar/b2-tools/4.4.2/libexec/lib/python3.13/site-packages/b2sdk/_internal/b2http.py", line 597, in _translate_and_retry
return cls._translate_errors(fcn, post_params)
~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^
File "/opt/homebrew/Cellar/b2-tools/4.4.2/libexec/lib/python3.13/site-packages/b2sdk/_internal/b2http.py", line 525, in _translate_errors
raise interpret_b2_error(
...<5 lines>...
)
b2sdk._internal.exception.ServiceError: 503 service_unavailable vault cannot start new uploads
INFO:b2sdk._internal.b2http:Pausing thread for 64 seconds because that is what the default exponential backoff is