Upgrading drupal 6 to drupal 8 – unable to access drupal 6 website to back up and copy data

Hi 

I hope you can help me with something.

I have an old drupal 6 website i wanted to upgrade to drupal 8.  I understand there is no way to do a simple backup / restore so i have built the drupal 8 site seperately and i am slowly copying the data from the old to the new site.  The problem i am having is that recently my old drupal 6 site has become unresponsive and no matter what link i click on whether it be frontend or backend it only defaults me to the front end home page.  The only back end link that works is the update.php and nothing else connects properly.  Due to this fact i am unable to get hold of the rest of the content to transfer it over.

I am unable to get into error log to find out why this may be happening.  Could this be a permissions issue or a server end problem potentially?

Any help you could give me would be very much appreciated.

Thanks

Tim

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