when I try to upload to the WordPress it gets install but shows this error why?

Fatal error: Uncaught Error: Call to undefined function is_plugin_active() in C:xampphtdocswordpresswp-content hemeslusionheader.php:16 Stack trace: #0 C:xampphtdocswordpresswp-includes emplate.php(730): require_once() #1 C:xampphtdocswordpresswp-includes emplate.php(676): load_template('C:\xampp\htdocs...', true, Array) #2 C:xampphtdocswordpresswp-includesgeneral-template.php(48): locate_template(Array, true, true, Array) #3 C:xampphtdocswordpresswp-content hemeslusionindex.php(2): get_header() #4 C:xampphtdocswordpresswp-includes emplate-loader.php(106): include('C:\xampp\htdocs...') #5 C:xampphtdocswordpresswp-blog-header.php(19): require_once('C:\xampp\htdocs...') #6 C:xampphtdocswordpressindex.php(17): require('C:\xampp\htdocs...') #7 {main} thrown in C:xampphtdocswordpresswp-content hemeslusionheader.php on line 16

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