Nginx invalid URL path prefix .. while sending to client

I have the following server settings which work for one URL but seem to fail on another URL.

location / {


    proxy_buffers 16 4k;
    proxy_buffer_size 2k;       


    proxy_set_header X-Real-IP  $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    proxy_set_header X-Forwarded-Proto https;
    proxy_set_header X-Forwarded-Port 443;

    proxy_pass http://10.4.1.81/;


    # This is used to handle the multiple redirect 301 that the server is doing
    proxy_intercept_errors on;
    error_page 301 302 307 = @handle_redirects;     


}   

location @handle_redirects {
    set $saved_redirect_location '$upstream_http_location';
    proxy_pass $saved_redirect_location;
}   

When I go to the following URL:

https://lfdocs.mohave.gov/bos/0/doc/1652027/Page1.aspx

I get the following error from Nginx

2020/12/03 19:10:40 [error] 31251#31251: *1 invalid URL prefix in "/bos/CookieCheck.aspx?redirect=%2fbos%2fDocView.aspx%3fdbid%3d0%26id%3d1652027%26page%3d1" while sending to client, client: 10.10.82.151, server: lfdocs.mohave.gov, request: "GET /bos/0/doc/1652027/Page1.aspx HTTP/2.0", host: "lfdocs.mohave.gov"

I did some research but I can't seem to figure it out. Any advice?

Thanks

Update

Here is what seems to be the problem the ones that valid are the ones with a valid URL. When it fails it's because the URL is invalid.

1. Using echo $saved_redirect_location;

   Success

   URL:

   https://lfdocs.mohave.gov/Forms/RequestToSpeak

   Return:

   https://10.4.1.81/Forms/RequestToSpeak

   Fails:

   URL:

   https://lfdocs.mohave.gov/bos/0/doc/1652027/Page1.aspx

   Returns:

   /bos/CookieCheck.aspx?redirect=%2fbos%2fDocView.aspx%3fdbid%3d0%26id%3d1652027%26page%3d1

2. Using echo http://10.4.1.81$saved_redirect_location;

   Fails

   URL:

   https://lfdocs.mohave.gov/Forms/RequestToSpeak

   Return:

   http://10.4.1.81https://10.4.1.81/Forms/RequestToSpeak

   Success

   URL:

   https://lfdocs.mohave.gov/bos/0/doc/1652027/Page1.aspx

   Return:

   http://10.4.1.81/bos/CookieCheck.aspx?redirect=%2fbos%2fDocView.aspx%3fdbid%3d0%26id%3d1652027%26page%3d1

using $saved_redirect_location to proxy_pass is there a way to check if the domain exists and if not to add it?

Update

My solution was to do the following:

   location @handle_redirects {
    set $saved_redirect_location '$upstream_http_location';

    # If IP exists just proxy pass
    if ($saved_redirect_location ~* "10.4.1.81") {
        proxy_pass $saved_redirect_location;
    }

    # If IP doesnt exist append it first
    if ($saved_redirect_location !~* "10.4.1.81") {
        proxy_pass http://10.4.1.81$saved_redirect_location;
    }       
}