# Launch client jar signature is invalid

**URL:** <https://forum.inductiveautomation.com/t/launch-client-jar-signature-is-invalid/110979>\
**Category:** Ignition\
**Tags:** designer\
**Created:** [September 25, 2025, 5:15pm UTC](https://forum.inductiveautomation.com/t/launch-client-jar-signature-is-invalid/110979 "2025-09-25T17:15:17Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Collin\_Hodges](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@Collin\_Hodges](https://forum.inductiveautomation.com/u/Collin_Hodges)\
**Post date:** [September 25, 2025, 5:15pm UTC](https://forum.inductiveautomation.com/t/launch-client-jar-signature-is-invalid/110979/1 "2025-09-25T17:15:17Z")

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I just upgraded one of my gateways to 8.3. I installed the latest version of designer, and now my gateways that are not updated to 8.3 I get “Launch client jar Invalid - This launch client jar signature is invalid. Contact and administrator.”

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**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:** [September 25, 2025, 5:45pm UTC](https://forum.inductiveautomation.com/t/launch-client-jar-signature-is-invalid/110979/2 "2025-09-25T17:45:53Z")

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If your 8.1 gateways are older than the signing jar, you need to either upgrade the gateways (so that a signed jar is distributed) or adjust the 8.3 designer launcher to allow unsigned jars (worse for security). See advice in this thread:

> [@Launch client jar invalid](https://forum.inductiveautomation.com/t/launch-client-jar-invalid/109145/7):
>
> Try closing the Designer Launcher first and then change the value to LENIENT

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<div class="post-metadata">

**Author:** ![Collin\_Hodges](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@Collin\_Hodges](https://forum.inductiveautomation.com/u/Collin_Hodges)\
**Post date:** [September 25, 2025, 5:57pm UTC](https://forum.inductiveautomation.com/t/launch-client-jar-signature-is-invalid/110979/3 "2025-09-25T17:57:37Z")

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I just tried this and still had no success. The gateway I am trying to connect to is 8.1.31. It is one that I can not upgrade right now. Any other ideas?

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**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:** [September 25, 2025, 5:59pm UTC](https://forum.inductiveautomation.com/t/launch-client-jar-signature-is-invalid/110979/4 "2025-09-25T17:59:34Z")

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Make sure there are no instances of the designer launcher running, and make sure that your edit actually went through. There is also `LOOSE`, weaker than `LENIENT`: [Launchers and Workstation | Ignition User Manual](https://docs.inductiveautomation.com/docs/8.3/launchers-and-workstation#signature-verification)

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<div class="post-metadata">

**Author:** ![Collin\_Hodges](https://avatars.discourse-cdn.com/v4/letter/c/f9ae1b/32.png) [@Collin\_Hodges](https://forum.inductiveautomation.com/u/Collin_Hodges)\
**Post date:** [September 25, 2025, 6:03pm UTC](https://forum.inductiveautomation.com/t/launch-client-jar-signature-is-invalid/110979/5 "2025-09-25T18:03:03Z")

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I tried a couple more times and it did work!! Thanks for your help!

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**Author:** ![cdunn.home](https://avatars.discourse-cdn.com/v4/letter/c/45deac/32.png) [@cdunn.home](https://forum.inductiveautomation.com/u/cdunn.home)\
**Post date:** [October 16, 2025, 11:54am UTC](https://forum.inductiveautomation.com/t/launch-client-jar-signature-is-invalid/110979/6 "2025-10-16T11:54:11Z")

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> [@Launch client jar invalid](https://forum.inductiveautomation.com/t/launch-client-jar-invalid/109145/7):
>
> closing the Designer Launcher

This is a small, but critical step!