If you have a proxy in place the best path forward would be to make this customization via the proxy server you're using due to the fact that the changes in BitBucket itself will revert after an upgrade, etc. Here are some resources you can use to create error pages in the environment you're using as a Proxy:
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After spinning my wheels trying to get organized enough to write a book for National Novel Writing Month (NaNoWriMo) I took my affinity for Atlassian products from my work life and decided to tr...
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