# HTTP ERROR 500 java.lang.NoClassDefFoundError

**URL:** <https://forum.inductiveautomation.com/t/http-error-500-java-lang-noclassdeffounderror/39379>\
**Category:** Ignition\
**Tags:** ignition79\
**Created:** [October 5, 2020, 3:39pm UTC](https://forum.inductiveautomation.com/t/http-error-500-java-lang-noclassdeffounderror/39379 "2020-10-05T15:39:21Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![patrick.garceau](https://avatars.discourse-cdn.com/v4/letter/p/76d3ee/32.png) [@patrick.garceau](https://forum.inductiveautomation.com/u/patrick.garceau)\
**Post date:** [October 5, 2020, 3:39pm UTC](https://forum.inductiveautomation.com/t/http-error-500-java-lang-noclassdeffounderror/39379/1 "2020-10-05T15:39:21Z")

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## HTTP ERROR 500 java.lang.NoClassDefFoundError: com/inductiveautomation/ignition/gateway/web/components/LaunchLink$Applet

The gateway is working, the designer is working, but unable to go to the gateway web page.  
Restarted the gateway, no effect.

Any idea

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**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:** [October 5, 2020, 4:04pm UTC](https://forum.inductiveautomation.com/t/http-error-500-java-lang-noclassdeffounderror/39379/2 "2020-10-05T16:04:20Z")

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Is this Ignition 7.9 or 8+ ? The latter has no support for applets.

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<div class="post-metadata">

**Author:** ![patrick.garceau](https://avatars.discourse-cdn.com/v4/letter/p/76d3ee/32.png) [@patrick.garceau](https://forum.inductiveautomation.com/u/patrick.garceau)\
**Post date:** [October 5, 2020, 4:20pm UTC](https://forum.inductiveautomation.com/t/http-error-500-java-lang-noclassdeffounderror/39379/3 "2020-10-05T16:20:30Z")

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I did choose ignition 7.9, just saw that the forum included 8.0.  
So, it is 7.9. Sorry for the confusion.

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**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:** [October 5, 2020, 4:23pm UTC](https://forum.inductiveautomation.com/t/http-error-500-java-lang-noclassdeffounderror/39379/4 "2020-10-05T16:23:08Z")

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Can you post the full error and stack trace somewhere or upload your logs?

Did you do an upgrade recently or something like that?