# JSON Module Error, Caused by: org.python.core.PyException: LookupError: unknown encoding 'hex' **URL:** \ **Category:** Ignition\ **Tags:** perspective\ **Created:** [July 8, 2025, 7:11am UTC](https://forum.inductiveautomation.com/t/json-module-error-caused-by-org-python-core-pyexception-lookuperror-unknown-encoding-hex/108217 "2025-07-08T07:11:21Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Senthoor\_Mani\_M](https://avatars.discourse-cdn.com/v4/letter/s/e19adc/32.png) [@Senthoor\_Mani\_M](https://forum.inductiveautomation.com/u/Senthoor_Mani_M)\ **Post date:** [July 8, 2025, 7:11am UTC](https://forum.inductiveautomation.com/t/json-module-error-caused-by-org-python-core-pyexception-lookuperror-unknown-encoding-hex/108217/1 "2025-07-08T07:11:21Z")
Hello all, In our Ignition Perspective project, we've encountered a module error related to the JSON library. This issue is frequently triggering errors that are flooding our gateway logs. The Error is Below: ` Traceback (most recent call last): File "", line 3, in runAction File "/usr/local/bin/ignition/user-lib/pylib/json/ __init__.py", line 108, in from .decoder import JSONDecoder File "/usr/local/bin/ignition/user-lib/pylib/json/decoder.py", line 24, in NaN, PosInf, NegInf = _floatconstants() File "/usr/local/bin/ignition/user-lib/pylib/json/decoder.py", line 18, in _floatconstants _BYTES = '7FF80000000000007FF0000000000000'.decode('hex') LookupError: unknown encoding 'hex'` Image of the Error: ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/5/3/53fdaf722b70a392becda0e1fdd1702dcdf30563.png) ``` If Anyone has encountered this issue before, please share your insights or solutions. Your assistance would be greatly appreciated. ``` Thanks. ---
**Author:** ![pascal.fragnoud](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pascal.fragnoud/32/24728_2.png) [@pascal.fragnoud](https://forum.inductiveautomation.com/u/pascal.fragnoud)\ **Post date:** [July 8, 2025, 7:24am UTC](https://forum.inductiveautomation.com/t/json-module-error-caused-by-org-python-core-pyexception-lookuperror-unknown-encoding-hex/108217/2 "2025-07-08T07:24:01Z")
Well... How about you show us the code ? And not just an image of the code. Format it properly. PS: Don't ping people. ---
**Author:** ![Senthoor\_Mani\_M](https://avatars.discourse-cdn.com/v4/letter/s/e19adc/32.png) [@Senthoor\_Mani\_M](https://forum.inductiveautomation.com/u/Senthoor_Mani_M)\ **Post date:** [July 8, 2025, 7:30am UTC](https://forum.inductiveautomation.com/t/json-module-error-caused-by-org-python-core-pyexception-lookuperror-unknown-encoding-hex/108217/3 "2025-07-08T07:30:26Z")
The code in Import json that is, ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/9/f/9f25dec3c93d6337487684285b9a3f44edb884b5.png) ---
**Author:** ![pascal.fragnoud](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pascal.fragnoud/32/24728_2.png) [@pascal.fragnoud](https://forum.inductiveautomation.com/u/pascal.fragnoud)\ **Post date:** [July 8, 2025, 7:33am UTC](https://forum.inductiveautomation.com/t/json-module-error-caused-by-org-python-core-pyexception-lookuperror-unknown-encoding-hex/108217/4 "2025-07-08T07:33:49Z")
What happens if you try to import it from somewhere else ? ---
**Author:** ![Senthoor\_Mani\_M](https://avatars.discourse-cdn.com/v4/letter/s/e19adc/32.png) [@Senthoor\_Mani\_M](https://forum.inductiveautomation.com/u/Senthoor_Mani_M)\ **Post date:** [July 8, 2025, 9:19am UTC](https://forum.inductiveautomation.com/t/json-module-error-caused-by-org-python-core-pyexception-lookuperror-unknown-encoding-hex/108217/5 "2025-07-08T09:19:36Z")
If i try to import json in script console it will through the below error, `Traceback (most recent call last): File "function:runAction", line 1, in runAction File "/usr/local/bin/ignition/user-lib/pylib/json/ **init**.py", line 108, in from .decoder import JSONDecoder File "/usr/local/bin/ignition/user-lib/pylib/json/decoder.py", line 24, in NaN, PosInf, NegInf = _floatconstants() File "/usr/local/bin/ignition/user-lib/pylib/json/decoder.py", line 18, in _floatconstants _BYTES = '7FF80000000000007FF0000000000000'.decode('hex') LookupError: unknown encoding 'hex'` ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [July 8, 2025, 11:16am UTC](https://forum.inductiveautomation.com/t/json-module-error-caused-by-org-python-core-pyexception-lookuperror-unknown-encoding-hex/108217/6 "2025-07-08T11:16:18Z")
Don't use `json` from jython's stdlib. Use Ignition's `system.util.jsonDecode()` and/or `system.util.jsonEncode()` functions--these are documented and supported. ---
**Author:** ![Transistor](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/transistor/32/3380_2.png) [@Transistor](https://forum.inductiveautomation.com/u/Transistor)\ **Post date:** [July 8, 2025, 1:57pm UTC](https://forum.inductiveautomation.com/t/json-module-error-caused-by-org-python-core-pyexception-lookuperror-unknown-encoding-hex/108217/7 "2025-07-08T13:57:27Z")
Please see [Wiki - how to post code on this forum](https://forum.inductiveautomation.com/t/wiki-how-to-post-code-on-this-forum/77831). Use this when posting code or error messages. Thanks. ---
**Author:** ![Senthoor\_Mani\_M](https://avatars.discourse-cdn.com/v4/letter/s/e19adc/32.png) [@Senthoor\_Mani\_M](https://forum.inductiveautomation.com/u/Senthoor_Mani_M)\ **Post date:** [July 9, 2025, 5:06am UTC](https://forum.inductiveautomation.com/t/json-module-error-caused-by-org-python-core-pyexception-lookuperror-unknown-encoding-hex/108217/8 "2025-07-09T05:06:17Z")
Okay, @pturmel Thanks for your Reply.