In an instance with particular base URL pattern like:
http://documentation.company.com/documentation (same word used for first name/part of domain and context path)
OR
http://localhost:8090/localhost

Steps to replicate

1. Create a page with link to another page in different space (e.g: in space 'TEST', page 'Glossary' is created with a text 'Next' linked to page 'Glossary2' in space 'TEMP')
2. Export page 'Glossary' to PDF
3. The text 'Next' will have link to http://documentation/display/TEM/Glossary2 instead of having http://documentation.company.com/documentation/display/TEM/Glossary2

The link is not preserved and shorten to invalid location.