Hello Rashida,
I was able to solve it, but I feel that JoomShaper should update their Quickstart packages and put both Joomla 4 and Joomla 5 versions, and obviously support PHP 8.1 onwards. My suggestion is to try to go with the minimum requirements supported and in some cases, recommended by Joomla.
This is what I did:
- I downgraded PHP 8.1 to PHP 7.4 at my hosting provider.
- I installed the quickstart package of the Fixter template for Joomla 4.
- I upgraded both Joomla and the extensions that come with the quickstart package offered by JoomShaper.
- When I managed to upgrade to Joomla 4.4.4, I was able to upgrade the PHP version back to 8.1.
- I upgraded to Joomla 5.
Now the site is working properly. No problems with any of the JoomShaper extensions, including the template.
I repeat... JoomShaper needs to put more love in the quickstart packages. Especially on older templates like Fixter.