Problem

After updating your Bamboo license key in the <bamboo-home>/bamboo.cfg.xml file, the following error shows in the UI and atlassian-bamboo.log:

Bamboo bootstrap failed: Failed to parse config file: Error on line XX of document : Element type "part-of-key-here" must be followed by either attribute specifications, ">" or "/>".

Cause

Some license keys now contain the < symbol, which is a special character in XML.

Resolution

To resolve this issue, please replace the < symbol in your new license key with its encoded equivalent, <. 

For example, for the following randomly-generated string:

r6SP4kIvsXT4ETL3rzPLPKmQKspQfpGs83IgNy4EQtStM4M4R9EoYoj7AUq3CBJP<FNzqmgfhaL8SfcCxX9jbyM92fxyWL3nbMsdosC<z02PhuWSvjuY4hgWloOhmbEs

It would need to be replaced with:

r6SP4kIvsXT4ETL3rzPLPKmQKspQfpGs83IgNy4EQtStM4M4R9EoYoj7AUq3CBJP<FNzqmgfhaL8SfcCxX9jbyM92fxyWL3nbMsdosC<z02PhuWSvjuY4hgWloOhmbEs