Author: Richard Johnson
Keywords: upgrading DITA Open Toolkit, upgrading, overview, things to consider before, DTDs, preserving during upgrade process, preserving customized during upgrade process, preserving during upgrade process

# Upgrade considerations

Before upgrading to a new version of DITA Open Toolkit, be sure to back up your current version so you can reapply modifications after your Toolkit upgrade. Such modifications might include:

- Specialization DTDs you added to the dtd directory and the corresponding updates you made to the catalog-dita-template.xml file
- XSLT stylesheets you have added to the xsl directory to override the standard stylesheets
- Plug-ins you have installed
- Catalogs for XML editors

Parent topic: Installation overview
Related concepts
DITA Tookit distributions
Installation considerations