Can't add product and edit product redirect's to categories

[naeem23]

Hi, I am using zen cart v1.3.8a for a longtime with php version 5.3. It's working fine with the current server (http://asadirect.co.uk/). Few days ago I copy the whole project to a new server along with database. This time I am using php version 5.6 as I can't downgrade further. The store front is working fine there too. (new site link http://leaflet-distribution.britishpost.co.uk/) But the problem is in admin dashboard. I can view old categories and product. But can't add new product as "+ New" button doesn't show any options to add product. Neither I can't edit existing product. When I click on edit button it redirect me to the category page.
Please help me figure out the issues.

[lat9]

Hi, I am using zen cart v1.3.8a for a longtime with php version 5.3. It's working fine with the current server (http://asadirect.co.uk/). Few days ago I copy the whole project to a new server along with database. This time I am using php version 5.6 as I can't downgrade further. The store front is working fine there too. (new site link http://leaflet-distribution.britishpost.co.uk/) But the problem is in admin dashboard. I can view old categories and product. But can't add new product as "+ New" button doesn't show any options to add product. Neither I can't edit existing product. When I click on edit button it redirect me to the category page.
Please help me figure out the issues.

If I remember correctly, v1.3.8a works fine with PHP versions as high as 5.4. Running that 10+ years-old code on PHP 5.6 could easily be the source of your issue. Unfortunately, I no longer have a working installation that uses zc138a to see for myself.

Since you can't use a version of PHP prior to 5.6, I suggest that it's time to upgrade.