What is PHP open_basedir
It limits the files that can be accessed by PHP to the specified
directory-tree, including the file itself. This directive is NOT
affected by whether Safe Mode is turned On or Off.
When a script tries to access the file system, for example using
include, or fopen(), the location of the file is checked. When the
file is outside the specified directory-tree, PHP will refuse to
access it. All symbolic links are resolved, so it's not possible to
avoid this restriction with a symlink. If the file doesn't exist then
the symlink couldn't be resolved and the filename is compared to (a
resolved) open_basedir.
open_basedir can affect more than just filesystem functions; for
example if MySQL is configured to use mysqlnd drivers, LOAD DATA
INFILE will be affected by open_basedir. Much of the extended
functionality of PHP uses open_basedir in this way.
The special value . indicates that the working directory of the script
will be used as the base-directory. This is, however, a little
dangerous as the working directory of the script can easily be changed
with chdir().
In httpd.conf, open_basedir can be turned off (e.g. for some virtual
hosts) the same way as any other configuration directive with
"php_admin_value open_basedir none".
Under Windows, separate the directories with a semicolon. On all other
systems, separate the directories with a colon. As an Apache module,
open_basedir paths from parent directories are now automatically
inherited.
The restriction specified with open_basedir is a directory name, not a
prefix.
The default is to allow all files to be opened.
Reference PHP.NET, 1
Conclusion
You have used open_basedir, and you did not update the path.
Additionally, i believe you that this Question should be asked on Superuser, as the evidence tells me that you are not using a Business Related environment.
php.ini (on Debian 10)
; open_basedir, if set, limits all file operations to the defined directory
; and below. This directive makes most sense if used in a per-directory
; or per-virtualhost web server configuration file.
; Note: disables the realpath cache
; http://php.net/open-basedir
;open_basedir =
That example, from above, is the DEFAULT setting on Debian 10 which is usually also the default on php.net. Which means you have changed it either manually. Or what I believe, since the path names included "panel_ssl_site" is that I think you're using an Admin-Panel and this leads to, that this Question goes into OFF-TOPIC. However, every Admin panel should be able to change this setting too, See regarding Reference StackOverflow to the same issue
