[BUG] fiftyone.core.service.ServerService failed to bind to port

[derickcjohn]

🗃️ Describe the problem

Not able to open FiftyOne at all. I'm running it as a script. I've installed Fiftyone in a virtual environment.

🖥️ Operating System Platform & Distribution

• Linux
• MacOS
• Windows
• Other (please specify)

💻 System Details

---

Processor Intel(R) Core(TM) i3-1005G1 CPU @ 1.20GHz (1.19 GHz)
Installed RAM 4.00 GB (3.77 GB usable)
System type 64-bit operating system, x64-based processor
Windows 11

🌐 Browser

Not applicable

⤵️ Installation type

---

• Package (pip)
• Source (git)

⌨️ Code to reproduce issue

---

import fiftyone as fo
import fiftyone.zoo as foz

dataset = foz.load_zoo_dataset("quickstart")
if __name__ == "__main__":
    session = fo.launch_app(dataset)
    session.wait(-1)

🐍 What version of Python?

---

Python 3.11.0

🔖 What version of FiftyOne?

FiftyOne v1.13.5, Voxel51, Inc.

🪵 Other info/logs

---

Dataset already downloaded
Loading 'quickstart'
 100% |███████████████████████████████████████████████████████████████████████████████████████| 200/200 [9.9s elapsed, 0s remaining, 32.6 samples/s]      
Dataset 'quickstart' created

Could not connect session, trying again in 10 seconds


Could not connect session, trying again in 10 seconds


Could not connect session, trying again in 10 seconds

Traceback (most recent call last):
  File "D:\Documents\Remote-x\yolo\dataset_viewer.py", line 14, in <module>
    session = fo.launch_app(dataset)
              ^^^^^^^^^^^^^^^^^^^^^^
  File "D:\Documents\Remote-x\yolo\yoo\Lib\site-packages\fiftyone\core\session\session.py", line 192, in launch_app
    _session = Session(
               ^^^^^^^^
  File "D:\Documents\Remote-x\yolo\yoo\Lib\site-packages\fiftyone\core\session\session.py", line 432, in __init__
    _register_session(self)
  File "D:\Documents\Remote-x\yolo\yoo\Lib\site-packages\fiftyone\core\session\session.py", line 1249, in _register_session
    _server_services[session.server_port] = fos.ServerService(
                                            ^^^^^^^^^^^^^^^^^^
  File "D:\Documents\Remote-x\yolo\yoo\Lib\site-packages\fiftyone\core\service.py", line 306, in __init__
    super().__init__()
  File "D:\Documents\Remote-x\yolo\yoo\Lib\site-packages\fiftyone\core\service.py", line 81, in __init__
    self.start()
  File "D:\Documents\Remote-x\yolo\yoo\Lib\site-packages\fiftyone\core\service.py", line 326, in start
    self._wait_for_child_port(port=port)
  File "D:\Documents\Remote-x\yolo\yoo\Lib\site-packages\fiftyone\core\service.py", line 171, in _wait_for_child_port
    return find_port()
           ^^^^^^^^^^^
  File "D:\Documents\Remote-x\yolo\yoo\Lib\site-packages\retrying.py", line 55, in wrapped_f
    return Retrying(*dargs, **dkw).call(f, *args, **kw)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "D:\Documents\Remote-x\yolo\yoo\Lib\site-packages\retrying.py", line 289, in call
    raise attempt.get()
          ^^^^^^^^^^^^^
  File "D:\Documents\Remote-x\yolo\yoo\Lib\site-packages\retrying.py", line 326, in get
    raise exc.with_traceback(tb)
  File "D:\Documents\Remote-x\yolo\yoo\Lib\site-packages\retrying.py", line 273, in call
    attempt = Attempt(fn(*args, **kwargs), attempt_number, False)
                      ^^^^^^^^^^^^^^^^^^^
  File "D:\Documents\Remote-x\yolo\yoo\Lib\site-packages\fiftyone\core\service.py", line 169, in find_port
    raise ServiceListenTimeout(etau.get_class_name(self), port)
fiftyone.core.service.ServiceListenTimeout: fiftyone.core.service.ServerService failed to bind to port 5151

🚀 Willingness to contribute

---

No, I cannot contribute a bug fix at this time

📸 Upload screenshots

---

No response

[AdonaiVera]

Hi @derickcjohn,
Thank you for reporting the issue. We’re here to help.

Could you share a bit more context about your environment? That would help us debug this better. In the meantime, here are a few things you can try:

First, try launching the app on a different port:

session = fo.launch_app(dataset, port=5149)

Sometimes another process is already using the default port, or there may be a conflict with another running session.

Second, try uninstalling your current version and installing the latest stable release:

pip install fiftyone==1.14.0

Another option is to add FiftyOne to your PYTHONPATH:

export PYTHONPATH=$PYTHONPATH:/path/to/fiftyone

We usually only need to do this when installing from source, but it could also help if you have multiple versions installed, or if there is a naming conflict with your current folder.

It’s a bit hard to debug further without more context, but if you share your setup, we can help you narrow it down.

[derickcjohn]

Hi @AdonaiVera, I had already tried changing the port number, but that didn't work; it would show the same error. I did the other things you suggested, but it still didn't work.
Here are the installed packages in my venv:
`Package Version

---

absl-py 2.4.0
aiofiles 25.1.0
annotated-types 0.7.0
anyio 4.12.1
appdirs 1.4.4
argcomplete 3.6.3
asgiref 3.11.1
asttokens 3.0.1
astunparse 1.6.3
async-lru 2.3.0
async-timeout 5.0.1
attr 0.3.1
attrs 26.1.0
azure-core 1.39.0
azure-storage-blob 12.28.0
backports.zstd 1.3.0
bcrypt 5.0.0
beautifulsoup4 4.14.3
black 26.3.1
bleach 5.0.1
boto3 1.42.73
botocore 1.42.73
brotli 1.2.0
cachetools 6.2.6
certifi 2026.2.25
cffi 2.0.0
charset-normalizer 3.4.5
click 8.3.1
cmap 0.7.2
colorama 0.4.6
contourpy 1.3.3
croniter 6.2.2
cross-web 0.4.1
cryptography 46.0.5
cycler 0.12.1
dacite 1.9.2
datamodel-code-generator 0.26.1
decorator 5.2.1
defusedxml 0.7.1
Deprecated 1.3.1
dill 0.4.1
distro 1.9.0
Django 5.1.15
django-annoying 0.10.6
django-cors-headers 4.7.0
django-csp 3.7
django-debug-toolbar 3.2.1
django-environ 0.10.0
django-extensions 3.2.3
django-filter 24.3
django-migration-linter 5.2.0
django-ranged-fileresponse 0.1.2
django-rq 3.1
django-storages 1.12.3
django-user-agents 0.4.0
djangorestframework 3.15.2
djangorestframework_simplejwt 5.5.1
dnspython 2.8.0
drf-dynamic-fields 0.3.0
drf-flex-fields 0.9.5
drf-generators 0.3.0
drf-spectacular 0.28.0
email-validator 2.3.0
exceptiongroup 1.3.1
executing 2.2.1
expiringdict 1.2.2
Faker 40.11.0
fiftyone 1.14.0
fiftyone-brain 0.21.5
fiftyone_db 1.4.1
filelock 3.25.2
flatbuffers 25.12.19
fonttools 4.62.1
fsspec 2026.2.0
ftfy 6.3.1
gast 0.7.0
gdown 5.2.1
genson 1.3.0
glob2 0.7
google-api-core 2.30.0
google-auth 2.49.1
google-cloud-appengine-logging 1.8.0
google-cloud-audit-log 0.4.0
google-cloud-core 2.5.0
google-cloud-logging 3.14.0
google-cloud-storage 3.10.0
google-crc32c 1.8.0
google-pasta 0.2.0
google-resumable-media 2.8.0
googleapis-common-protos 1.73.0
graphql-core 3.2.8
grpc-google-iam-v1 0.14.3
grpcio 1.78.0
grpcio-status 1.78.0
h11 0.16.0
h2 4.3.0
h5py 3.14.0
hpack 4.1.0
httpcore 1.0.9
httpx 0.28.1
humanize 4.15.0
Hypercorn 0.18.0
hyperframe 6.1.0
idna 3.11
ijson 3.5.0
ImageIO 2.37.3
imgviz 2.0.0
importlib_metadata 8.7.1
inflate64 1.0.4
inflect 5.6.2
inflection 0.5.1
ipython 9.10.0
ipython_pygments_lexers 1.1.1
isodate 0.7.2
isort 5.13.2
jedi 0.19.2
Jinja2 3.1.6
jiter 0.13.0
jmespath 1.1.0
joblib 1.5.3
jsf 0.11.2
jsonlines 4.0.0
jsonpatch 1.33
jsonpointer 3.1.0
jsonschema 4.26.0
jsonschema-specifications 2025.9.1
keras 3.13.2
kiwisolver 1.5.0
label-studio 1.23.0
label-studio-sdk 2.0.18
launchdarkly-server-sdk 8.2.1
lazy-loader 0.5
libclang 18.1.1
loguru 0.7.3
lxml 6.0.2
lxml_html_clean 0.4.4
markdown-it-py 4.0.0
MarkupSafe 3.0.3
matplotlib 3.10.8
matplotlib-inline 0.2.1
mdurl 0.1.2
ml_dtypes 0.5.4
mongoengine 0.29.3
motor 3.6.1
mpmath 1.3.0
multivolumefile 0.2.3
mypy_extensions 1.1.0
namex 0.1.0
narwhals 2.18.0
natsort 8.4.0
networkx 3.6.1
nltk 3.9.3
numpy 2.4.3
onnxruntime 1.24.4
openai 1.109.1
opencv-python 4.13.0.92
opencv-python-headless 4.13.0.92
opentelemetry-api 1.40.0
opt_einsum 3.4.0
optree 0.19.0
ordered-set 4.0.2
osam 0.3.1
packaging 26.0
pandas 3.0.1
paramiko 3.5.1
parso 0.8.6
pathspec 1.0.4
pillow 12.1.1
pip 22.3
platformdirs 4.9.4
plotly 6.6.0
polars 1.39.0
polars-runtime-32 1.39.0
pprintpp 0.4.0
priority 2.0.0
prompt_toolkit 3.0.52
proto-plus 1.27.1
protobuf 6.33.6
psutil 7.2.2
psycopg 3.3.3
psycopg-binary 3.3.3
pure_eval 0.2.3
py7zr 1.1.0
pyarrow 22.0.0
pyasn1 0.6.3
pyasn1_modules 0.4.2
pybcj 1.0.7
pyboxen 1.3.0
pycparser 3.0
pycryptodomex 3.23.0
pydantic 2.12.5
pydantic_core 2.41.5
pydash 8.0.6
Pygments 2.19.2
PyJWT 2.12.1
pymongo 4.9.2
PyNaCl 1.6.2
pyparsing 3.3.2
pyppmd 1.3.1
PyQt5 5.15.11
PyQt5-Qt5 5.15.2
PyQt5_sip 12.18.0
pyRFC3339 2.1.0
PySocks 1.7.1
python-dateutil 2.9.0.post0
python-json-logger 2.0.4
pytokens 0.4.1
pytz 2022.7.1
PyYAML 6.0.3
rarfile 4.2
redis 5.2.1
referencing 0.37.0
regex 2026.2.28
requests 2.32.5
requests-file 3.0.1
requests-mock 1.12.1
retrying 1.4.2
rich 14.3.3
rpds-py 0.30.0
rq 2.6.1
rstr 3.2.2
rtree 1.4.1
rules 3.4
s3transfer 0.16.0
scikit-image 0.26.0
scikit-learn 1.8.0
scipy 1.17.1
semver 3.0.4
sentry-sdk 2.55.0
setuptools 82.0.1
six 1.17.0
smart_open 7.5.1
sniffio 1.3.1
sortedcontainers 2.4.0
soupsieve 2.8.3
sqlparse 0.5.5
sse-starlette 0.10.3
sseclient-py 1.9.0
stack-data 0.6.3
starlette 0.52.1
strawberry-graphql 0.291.3
sympy 1.14.0
tabulate 0.9.0
tensorflow 2.21.0
termcolor 3.3.0
texttable 1.7.0
threadpoolctl 3.6.0
tifffile 2026.3.3
tldextract 5.3.1
toml 0.10.2
torch 2.10.0
torchvision 0.25.0
tqdm 4.67.3
traitlets 5.14.3
typing_extensions 4.15.0
typing-inspection 0.4.2
tzdata 2025.3
tzlocal 5.3.1
ua-parser 1.0.1
ua-parser-builtins 202603
ujson 5.12.0
ultralytics 8.4.21
ultralytics-thop 2.0.18
universal-analytics-python3 1.1.1
uritemplate 4.2.0
urllib3 2.6.3
user-agents 2.2.0
uuid_utils 0.14.1
voxel51-eta 0.15.4
wcwidth 0.6.0
webencodings 0.5.1
wheel 0.46.3
win32_setctime 1.2.0
wrapt 2.1.2
wsproto 1.3.2
xmljson 0.2.1
xmltodict 1.0.4
zipp 3.23.0`

[benjaminpkane]

The server can be started directly via python /path/to/fiftyone/server/main.py. That may reveal the issue.

[derickcjohn]

@benjaminpkane , shows it cannot connect to mongod

Starting execution store notification service daemon...
[2026-04-02 12:58:27 +0530] [8020] [INFO] Running on http://127.0.0.1:5151 (CTRL + C to quit)
Mongo change stream is not available. Falling back to polling.
[2026-04-02 12:59:41 +0530] [8020] [ERROR] Error in ASGI Framework

File "D:\Documents\Remote-x\yolo\yoo\Lib\site-packages\fiftyone\core\odm\database.py", line 349, in _validate_db_version
    raise ConnectionError("Could not connect to `mongod`") from e
ConnectionError: Could not connect to `mongod