Gnucash backends

[Colin Law]

On 20 March 2018 at 19:05, Jonathan Silvey <jonathan.silvey at gmail.com> wrote:
> I have been using GnuCash on Linux Mint for several years. As they were
> getting full, I decided to start a new file and this has been running
> successfully for three weeks. When I try to run the old data, the relevant
> files are there but when I click on them, I get 'No suitable back-end found

That error may mean you are trying to open a file that is not a
gnucash accounts file.
What is the name of the file you are trying to open?  It will normally
be something.gnucash

Colin