This page provides some advice on dealing with commonly reported problems you may encounter. Stencila and its various components are still in development phase and so you may find that there are some glitches. We are working on fixing them but in the meantime we ask you for patience and hope that the advice below will be helpful. Thank you for your understanding!

Stencila Execution Contexts

Can't see if execution contexts are working

Stencila execution contexts, so the "engines" that allow you to run the code (R, Python and so on) within Stencila documents, run as hosts either on your local machine (if you are using the Desktop version) or on the cloud (that usually be the case, if you use Stencila Hub).
If you are using Stencila Desktop and would like to check if the execution contexts are running correctly, you can do that through the command line.
If you are running Linux or Mac OS, open a terminal and type:

ls /tmp/stencila/hosts -lt

This should result in an output similar to the one below:

total 16
-rw------- 1 nokome nokome  514 Feb 22 12:36 r-host-293d576d-5e56-4dde-9196-dc67aea40a55.json
-rw------- 1 nokome nokome   64 Feb 22 12:36 r-host-293d576d-5e56-4dde-9196-dc67aea40a55.key
-rw------- 1 nokome nokome 1281 Feb 22 12:36 node-host-a2163786-8d50-4fe2-a64f-b942ff165cea.json
-rw------- 1 nokome nokome   64 Feb 22 12:36 node-host-a2163786-8d50-4fe2-a64f-b942ff165cea.key

The node-host is the one embedded in Stencila Desktop. It starts as soon as you launch the application. The r-host starts as soon as you create an R cell within Stencila document. You can see more details of the r-host by looking at its JSON file, in the example above it is r-host-293d576d-5e56-4dde-9196-dc67aea40a55.json.

cat /tmp/stencila/hosts/r-host-293d576d-5e56-4dde-9196-dc67aea40a55.json 
   "stencila": {
     "package": "r",<br/>
     "version": "0.28.3"
   "id": "r-host-293d576d-5e56-4dde-9196-dc67aea40a55",
   "spawn": ["/usr/bin/Rscript", "-e", "stencila:::spawn()"],
   "environs": [
       "id": "local",
       "name": "local",
       "version": ""
   "types": {
     "RContext": {
       "name": "RContext",
       "client": "ContextHttpClient"
   "machine": [],
   "process": {
     "pid": 4142
   "servers": {
     "http": {
       "url": ""

You can confirm that the r-host is running by pinging it's IP: curl or by using its pid. For the example above it would be ps 4142. Stencila Desktop uses the information in that JSON file to connect to an execution context. If the process running the context has died for some reason, it could be that the Desktop is still trying to connect to it and hence you are experiencing problems such as the code not being excecuted in a cell.

Stencila Desktop

Code output doesn't change and no error is displayed

First, try to delete the whole cell that became inactive and then create a new cell, re-entering the code. If that doesn't help, it may be that what happened is the execution context you are using to run the code in the code cell became unavailable for Stencila Desktop to communicate with. Depending on which context you are using, R, Python or Jupyter, you may need to restart the context on your machine.

  • for R context, open an R session (either in an R shell or R Studio) and type stencila::start();
  • for Python or Jupyter Python context, open a terminal and type python -m stencila.

Stencila Converters

Converting files into a dar project results in an error Cannot read property 'length' of undefined

Most likely one of the files in the folder you are trying to convert is a csv file and our converter may be tripping over some empty cells. One of the solutions is not to convert the csv files into dar. You will still be able to manipulate them from within Stencila Desktop using your programming language of choice, just like you would in any other code editor. Another solution would be editing your csv files trying to find the empty cells and filling them in with a relevant information (such as NA) and then trying the conversion step once again.