It should be possible to import previous versions of Guitar Pro (like the *.gp5 files from version 5) and re-save them to the latest GPX format. Probably done by the default File ► Save as.. function.
Convert Guitar Pro 5 project to Guitar Pro 6 format.
We found 2 software records in the database related to .gp5 to .gpx file format conversion.
Microsoft Windows software - convert gp5 to gpx on Windows
Multi-track editor and music composer for guitars
Convert from gp5 file format
|Yes, Guitar Pro supports gpx file conversion as a target file type.||Yes||Yes||gpx editor||Yes||No||No||No|
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned gp5 to gpx. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Apple macOS / Mac OS X software - convert gp5 to gpx on OS X
Mac version of the popular tablature editor