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Most of our spaces use modified and styled left sidebar. With the demise of the Documentation theme, we restructured it to work with the default theme. There were a series of problems with this, the last one being discussed in CONF-41129. While we thought we were close to the end of these problems, the 2016-04-11 Cloud update broke us again as noted in the issue. This describes the automation we used to fix this.
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Fortunately, we standardized all of our space specific side-bars consistently with a single page in each space called _LeftSide. The workaround was to change a specific span macro to a div. We also decided to change the id to avoid potential conflicts with future Confluence modifications from PageTree to PageTree_override.
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