Rendering a large xls or xlsx spreadsheet can cause an OutOfMemory error in Confluence. We have seen this occur on OnDemand instances and behind-the-firewall instances.
Developers, please see the attachment PLM_stats.xls in this (private) support case for an example of a file that can cause this issue.
- Reduce the size of the spreadsheet to reduce the rendering required
- Increase the memory available to Confluence
- NB: If you use G1GC we would recommend turning that off. We have not done extensive testing but the collector it replaced (CMS) did not generally perform well with Confluence, and we have anecdotally seen some examples of G1GC causing problems with Confluence as well.