I could see following errors in the error log for my vBulletin 4.2.x forum:

Code:
2019-10-13 03:43:21.344864 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo_pre.php on line 279
2019-10-13 03:43:21.348586 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo_pre.php on line 86
2019-10-13 03:43:21.348728 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo_pre.php on line 129
2019-10-13 03:43:21.348820 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo_pre.php on line 130
2019-10-13 03:43:21.348890 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo_pre.php on line 131
2019-10-13 03:43:21.348956 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo_pre.php on line 132
2019-10-13 03:43:21.349202 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo.php on line 18
2019-10-13 03:43:21.349311 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo.php on line 19
2019-10-13 03:43:21.349402 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo.php on line 20
2019-10-13 03:43:21.349484 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo.php on line 21
2019-10-13 03:43:21.349598 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo.php on line 22
2019-10-13 03:43:21.349679 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo.php on line 23
2019-10-13 03:43:21.349760 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo.php on line 24
2019-10-13 03:43:21.349855 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo.php on line 25
2019-10-13 03:43:21.349936 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo.php on line 26
2019-10-13 03:43:21.350019 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo.php on line 27
2019-10-13 03:43:21.350103 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo.php on line 22
2019-10-13 03:43:21.359020 [NOTICE] [3993837] [1.2.3.4:45012] [STDERR] PHP Strict Standards:  Non-static method vBSEO_Storage::path() should not be called statically in /home/user/public_html/vbseo/includes/functions_vbseo_url.php on line 359
How to fix it so the function works in current PHP version? What apparently worked was following:

I tried to replace line:
function path($type = '')
in /vbseo/includes/functions_vbseo_pre.php
by:
public static function path($type = '')

megasoft.com is the author of this idea