# When I use webrtc exmple publish, the server displays the following error

**URL:** <https://community.wowza.com/t/when-i-use-webrtc-exmple-publish-the-server-displays-the-following-error/53805>\
**Category:** Hire a Consultant\
**Tags:** webrtc\
**Created:** [August 16, 2019, 8:01am UTC](https://community.wowza.com/t/when-i-use-webrtc-exmple-publish-the-server-displays-the-following-error/53805 "2019-08-16T08:01:42Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![long\_wang](https://avatars.discourse-cdn.com/v4/letter/l/f4b2a3/32.png) [@long\_wang](https://community.wowza.com/u/long_wang)\
**Post date:** [August 16, 2019, 8:01am UTC](https://community.wowza.com/t/when-i-use-webrtc-exmple-publish-the-server-displays-the-following-error/53805/1 "2019-08-16T08:01:42Z")

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**comment**  
server (500) WebSocketRunner.run : java.lang.NullPointerException|at com.wowza.wms.webrtc.sdp.WebRTCSDPTrack.toSDPString(WebRTCSDPTrack.java:75)|at com.wowza.wms.webrtc.sdp.WebRTCSDPInfo.toSDPString(WebRTCSDPInfo.java:66)|at com.wowza.wms.webrtc.sdp.WebRTCSDPInfo.toSDPString(WebRTCSDPInfo.java:52)|at com.wowza.wms.webrtc.model.WebRTCCommands.sendOffer(WebRTCCommands.java:268)|at com.wowza.wms.webrtc.http.HTTPWebRTCExchangeSessionInfo.handleMessage(HTTPWebRTCExchangeSessionInfo.java:122)|

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**Author:** ![Rose\_Power-Wowza\_Com](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/rose_power-wowza_com/32/431_2.png) [@Rose\_Power-Wowza\_Com](https://community.wowza.com/u/Rose_Power-Wowza_Com)\
**Post date:** [August 16, 2019, 4:06pm UTC](https://community.wowza.com/t/when-i-use-webrtc-exmple-publish-the-server-displays-the-following-error/53805/2 "2019-08-16T16:06:22Z")

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Thanks for posting and I’m sorry you’re getting errors @long wang. These errors suggest incorrect Application.xml configuration or perhaps VHost.xml not correct. WebRTC is an advanced workflow and our engineers can help you see what needs to be corrected through a support ticket. They do not debug in the forums however.

When you submit a ticket, our tech support team can view your files and run some tests to find the issue quickly.

[https://www.wowza.com/support/open-ticket](https://www.wowza.com/support/open-ticket)