# Why is dateutil library available on only some of my Ignition deployments? **URL:** \ **Category:** Ignition\ **Tags:** scripting, ignition81\ **Created:** [April 13, 2026, 4:55pm UTC](https://forum.inductiveautomation.com/t/why-is-dateutil-library-available-on-only-some-of-my-ignition-deployments/115047 "2026-04-13T16:55:43Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![tyler.bennett](https://avatars.discourse-cdn.com/v4/letter/t/f04885/32.png) [@tyler.bennett](https://forum.inductiveautomation.com/u/tyler.bennett)\ **Post date:** [April 13, 2026, 4:55pm UTC](https://forum.inductiveautomation.com/t/why-is-dateutil-library-available-on-only-some-of-my-ignition-deployments/115047/1 "2026-04-13T16:55:43Z")
Hi, we developed a feature to implement a maintenance calendar of sorts. We ended using `dateutil` and `dateutil.rrule` to support recurring events and such. Initially that library appeared to be built-in (included with Ignition) but as we have gone to deploy the feature to other servers we found that library is not present on some Ignition installations. I suspect the difference may be associated with Ignition modules that are installed on some and not others (Web Dev module and/or Kymera Influx DB module). I'm working to confirm that. Is anyone aware of other possibilities that may cause the `dateutil` library to be available on some Ignition deployments and not others? UPDATE: Both modules in question are installed on the Ignition server that is missing the `dateutil` library so missing modules does not appear to be the cause. ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [April 13, 2026, 4:59pm UTC](https://forum.inductiveautomation.com/t/why-is-dateutil-library-available-on-only-some-of-my-ignition-deployments/115047/2 "2026-04-13T16:59:21Z")
I don't think this is part of the standard python library. You or somebody else must have installed it on those servers. ---
**Author:** ![tyler.bennett](https://avatars.discourse-cdn.com/v4/letter/t/f04885/32.png) [@tyler.bennett](https://forum.inductiveautomation.com/u/tyler.bennett)\ **Post date:** [April 13, 2026, 5:13pm UTC](https://forum.inductiveautomation.com/t/why-is-dateutil-library-available-on-only-some-of-my-ignition-deployments/115047/3 "2026-04-13T17:13:53Z")
Indeed, it appears `dateUtil` was a dependency for the `boto3` library we added to `/usr/local/bin/ignition/user-lib/pylib/site-packages`. My confusion stemmed from the fact that I found `dateUtil` it at `/usr/local/bin/ignition/user-lib/pylib/dateutil` on one of our servers, rather than the `site-packages` directory where we intended our additional libraries to exist. Likely our own misplaced copy attempt. @Kevin.Herron, thanks for the quick response. ---
**Author:** ![paul-griffith](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/paul-griffith/32/37249_2.png) [@paul-griffith](https://forum.inductiveautomation.com/u/paul-griffith)\ **Post date:** [April 13, 2026, 10:37pm UTC](https://forum.inductiveautomation.com/t/why-is-dateutil-library-available-on-only-some-of-my-ignition-deployments/115047/4 "2026-04-13T22:37:42Z")
As an aside, I would discourage use of `dateutil` and `rrule`. It's very easy to keep around instances of the entire Jython interpreter (leading to significant memory leaks) if you start keeping user defined functions and classes around in stable threads, _and_ it's harder for the next person to do maintenance if they have to grok your whole scripting setup (vs using builtin platform elements like scheduled scripts).