# Why an Unexpected NoSuchElementException Exception? key not found: UNRECOGNIZED?

**URL:** <https://forum.canton.network/t/why-an-unexpected-nosuchelementexception-exception-key-not-found-unrecognized/7997>\
**Category:** App Development\
**Tags:** canton\
**Created:** [June 6, 2025, 5:25pm UTC](https://forum.canton.network/t/why-an-unexpected-nosuchelementexception-exception-key-not-found-unrecognized/7997 "2025-06-06T17:25:30Z")\
**Posts on this page:** 1\
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**Author:** ![WallaceKelly](https://yyz2.discourse-cdn.com/flex034/user_avatar/forum.canton.network/wallacekelly/32/5046_2.png) [@WallaceKelly](https://forum.canton.network/u/WallaceKelly)\
**Post date:** [June 6, 2025, 5:25pm UTC](https://forum.canton.network/t/why-an-unexpected-nosuchelementexception-exception-key-not-found-unrecognized/7997/2 "2025-06-06T17:25:37Z")

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This can be caused when there is an incompatibility between the compilation of the DAR and the Canton participant version.

- Use [Daml SDK version for a given DAR?](https://discuss.daml.com/t/daml-sdk-version-for-a-given-dar/7391) to check the SDK version used to compile the DAR.

- Use `curl -s http://localhost:7575/v2/version | jq .version` to query the participant version.

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