Hello,
That error in export template is coming from external library file RO CSVI uses in code. With RO CSVI 8.22.0 this library was updated and the updated version does not work with PHP 7.4 version. You must be having PHP7.4 version in your Joomla 3 site and so you see the error. I have updated this library to use previous version on your site and now export works. For your information RO CSVI 8.22.0 version is the last version to support Joomla3 which means RO CSVI will not have any updates anymore in Joomla3 and so library files updated now will not be overwritten. You can run export now and check.
Kind regards,
Tharuna
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