file_exists(): open_basedir restriction in effect. File(/tmp/log.htm)

Error : file_exists(): open_basedir restriction in effect. File(/tmp/log.htm) is not within the allowed path(s): (/home/admin/tmp)

I know you not supposed to change vendor files but in my case what helped was changing the project_name/vendor/dompdf/dompdf/src/Options.php line no: 296. I changed

Also read : No such File or Directory by using laravel-dompdf Package

Options.php

#project_namevendor/dompdf/dompdf/src/Options.php

$this->setTempDir(sys_get_temp_dir()); //remove
$this->setTempDir(storage_path('app/')); //added

If the problem still persists after the upgrade, try to clear cache using php artisan cache:clear and make sure that laravel /storage directory is accessible.

Also read : Laravel 7 PDF Generator Tutorial Using Dompdf