As far as I can tell PHP 7.4 got a bit stricter with its error handling.
In the-grid/frontend/the-grid-init.class.php on line 276 there is the following line.
if ($this->grid_options[‘mediaelement’] && $this->grid_options[‘mediaelement_ex’]) {
which results in the following error:
Trying to access array offset on value of type null
I was able to resolve this error by changing the line to:
if( is_array( $this->grid_options ) && array_key_exists( ‘mediaelement’, $this->grid_options ) && array_key_exists( ‘mediaelement’, $this->grid_options ) ) {