Hello,
Something really strange occurred. I copied my website to a temporary website, exported the database and upgraded from v1.7.5 to 8.1.5 in steps.
Everything is working good, I can access everything accept editing or add a new product.
When I navigate to the Products-page, I see all my products, except the images. I didn't copy the product images because there are more than 20k products. But I copied the images for 1 product for testing. I also cleared the cache, disabled the cache, set it to Force compilation (although the last 2 settings are for the front), disabled overrides, enabled Debug mode (double checked it by downloading the defines.inc.php file). But when I click on a product for editing or click the New Product-button, after a few seconds of loading, I get a white screen. No matter what I do, nothing shows up, not even a single letter or number.
After thinking, and thinking, maybe the htaccess.. Created new ones, and even deleted them but nothing. So my last idea is fault in the database with the product settings. But than, there would be an error, right?
Edit:
Already found 1 problem. There were a few files left in the overrides-folder from the previous shop.
Copied those files (for backup) and deleted them and deleted the cache in var->cache->dev + prod folders.
But now I have an out of memory:
Error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 20480 bytes)
Does it really need more than 256mb??
Any suggestions?