HTTPS access on Bitbucket 5.5

[mehran]

We are using Bitbucket on centos6.9 . We have upgraded the Bitbucket from 4.14 to 5.5 and we  followed the link below for configuring SSL on Bitbucket server.

https://confluence.atlassian.com/bitbucketserver/migrate-server-xml-customizations-to-bitbucket-properties-897811761.html

Bitbucket Server secured with SSL and additional connector to redirect HTTP requests

However, server keeps failing to start as logs are as below:

2017-11-29 12:16:27,921 ERROR [main]  o.s.b.d.LoggingFailureAnalysisReporter

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APPLICATION FAILED TO START
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Description:

The Tomcat connector configured to listen on port 7990 failed to start. The port may already be in use or the connector may be misconfigured.

Action:

Verify the connector's configuration, identify and stop any process that's listening on port 7990, or configure this application to listen on another port.

2017-11-29 12:16:27,929 INFO  [main]  c.a.b.i.boot.log.BuildInfoLogger Bitbucket 5.5.1 has shut down

[Lars Olav Velle]

bitbucket_home_5.5.1/shared/bitbucket.properties

server.secure=true
server.scheme=https
server.proxy-port=443
server.proxy-name=bitbucket.example.com