Positron is stuck at conneting to reticulate session. Any ideas why?

[jojo599k]

Hi there,

im trying to use reticulate with the Positron IDE and it does not work for me.
When using a R shell everything works fine. This seems to me that my setup with Positron could be incorrect and I have not found resources describing this error.

Im on a MacBook with M1 Chip and running Positron version is 1.103.0.

Positron Version: 2025.10.0 build 199
Code - OSS Version: 1.103.0
Commit: 81d0c98
Date: 2025-10-09T17:36:10.658Z
Electron: 37.2.3
Chromium: 138.0.7204.100
Node.js: 22.17.0
V8: 13.8.500258-electron.0
OS: Darwin arm64 24.6.0

I'm using R Version 4.5.1 and Python 3.11.14 in miniconda.

The problem is that the python shell/console is started but positron is stuck at Creating the Reticulate Python session: Connecting to the Reticulate session.

Below are logs from the Python Kernel which says that ERROR | Unable to initialize signal.

Logs from positron.positron-supervisor.Python (reticulate) Kernel

2025-10-15 12:53:50.532 [info] ** Begin kernel log for session Python (reticulate) (python-b431d004) at 15.10.2025, 12:53:50 **
Streaming kernel log file: /var/folders/y3/55x85nm16t9cqfyh2tp8c7n80000gn/T/kernel-python-b431d004.log
[Python] [PositronIPKernelApp] Using existing profile dir: '/Users/jojo599k/.ipython/profile_default'
[Python] [PositronIPKernelApp] Searching path ['/Users/jojo599k/.ipython/profile_default', '/opt/homebrew/Caskroom/miniconda/base/envs/data-mining/etc/ipython', '/usr/local/etc/ipython', '/etc/ipython'] for config files
[Python] [PositronIPKernelApp] Attempting to load config file: ipython_config.py
[Python] [PositronIPKernelApp] Looking for ipython_config in /etc/ipython
[Python] [PositronIPKernelApp] Looking for ipython_config in /usr/local/etc/ipython
[Python] [PositronIPKernelApp] Looking for ipython_config in /opt/homebrew/Caskroom/miniconda/base/envs/data-mining/etc/ipython
[Python] [PositronIPKernelApp] Looking for ipython_config in /Users/jojo599k/.ipython/profile_default
[Python] [PositronIPKernelApp] Attempting to load config file: ipython_kernel_config.py
[Python] [PositronIPKernelApp] Looking for ipython_kernel_config in /etc/ipython
[Python] [PositronIPKernelApp] Looking for ipython_kernel_config in /usr/local/etc/ipython
[Python] [PositronIPKernelApp] Looking for ipython_kernel_config in /opt/homebrew/Caskroom/miniconda/base/envs/data-mining/etc/ipython
[Python] [PositronIPKernelApp] Looking for ipython_kernel_config in /Users/jojo599k/.ipython/profile_default
[Python] [PositronIPKernelApp] Loading connection file /var/folders/y3/55x85nm16t9cqfyh2tp8c7n80000gn/T/connection-python-b431d004.json
[Python] [PositronIPKernelApp] Starting the kernel at pid: 57635
[Python] [PositronIPKernelApp] shell ROUTER Channel on port: 55557
[Python] [PositronIPKernelApp] stdin ROUTER Channel on port: 55560
[Python] [PositronIPKernelApp] control ROUTER Channel on port: 55556
[Python] [asyncio] Using selector: KqueueSelector
[Python] [asyncio] Using selector: KqueueSelector
[Python] [PositronIPKernelApp] iopub PUB Channel on port: 55558
[Python] [asyncio] Using selector: KqueueSelector
[Python] [PositronIPKernelApp] Heartbeat REP Channel on port: 55559
[Python] [PositronIPKernelApp] Connection file /var/folders/y3/55x85nm16t9cqfyh2tp8c7n80000gn/T/connection-python-b431d004.json with current information already exists
[Python] [PositronIPKernelApp] To connect another client to this kernel, use:
[Python] [PositronIPKernelApp]     --existing /var/folders/y3/55x85nm16t9cqfyh2tp8c7n80000gn/T/connection-python-b431d004.json
[Python] [PositronIPKernelApp] ERROR | Unable to initialize signal:
[Python] Traceback (most recent call last):
[Python]   File "/opt/homebrew/Caskroom/miniconda/base/envs/data-mining/lib/python3.11/site-packages/ipykernel/kernelapp.py", line 720, in initialize
[Python]     self.init_signal()
[Python]   File "/opt/homebrew/Caskroom/miniconda/base/envs/data-mining/lib/python3.11/site-packages/ipykernel/kernelapp.py", line 556, in init_signal
[Python]     signal.signal(signal.SIGINT, signal.SIG_IGN)
[Python]   File "/opt/homebrew/Caskroom/miniconda/base/envs/data-mining/lib/python3.11/signal.py", line 58, in signal
[Python]     handler = _signal.signal(_enum_to_int(signalnum), _enum_to_int(handler))
[Python]               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[Python] ValueError: signal only works in main thread of the main interpreter
[Python] [positron.utils] Calling ipykernel.thread.BaseThread.run with args: (), kwargs: {}
[Python] [positron.utils] Calling tornado.platform.asyncio.BaseAsyncIOLoop.start with args: (), kwargs: {}
[Python] [PositronIPKernelApp] Loading IPython extensions...
[Python] [PositronIPKernelApp] Loading IPython extension: storemagic
[Python] [asyncio] Using selector: KqueueSelector

Any ideas why this happens and what I could change or try out?
Thank you in advanced!

[dfalbel]

Hello @jojo599k

Thanks for reporting!

A new release of Ipykernel has affected support for reticulate within positron. I'm working on it.

While it's not solved, you can downgrade ipykernel by using reticulate::py_require("ipykernel<7") before starting the reticulate repl, or if you are using a local .venv, by downgrading the installed ipykernel version to some version below 7.0.

Sorry for the disruption.

[jtrecenti]

that solved my issue, thanks!

[dfalbel]

Nice! We have an issue opened in #9966 and the PR is already merged into ipykernel. Should be fixed once they release ipykernel 7.0.2