I checked quite many threads about this topic but was not able to solve the issue. When I open a category overview I don't get the thumbnails. Opening the product details I can see the main image and the smaller images in the slider below. So that shouldn't be any permission issues. Magento also generates the cache directory with 4 different image sizes.
My url to the thumbnail is:
find . -name "aaa_5_2_3.jpg" pub/media/catalog/product/cache/f9c7fbe9b524c081a3ccf800cbd963eb/a/a/aaa_5_2_3.jpg pub/media/catalog/product/cache/75eed2686e01eb22cb4050b2f40ddf97/a/a/aaa_5_2_3.jpg pub/media/catalog/product/cache/0f831c1845fc143d00d6d1ebc49f446a/a/a/aaa_5_2_3.jpg pub/media/catalog/product/cache/afad95d7734d2fa6d0a8ba78597182b7/a/a/aaa_5_2_3.jpg
I guess the identifier
(=f073062f50e48eb0f0998593e568d857) is wrong. Where does it come from? I tried to find the php file where the path is generated but couldn't find it.
php bin/magento setup:static-content:deploy didn't help either. That's why I think the identifier is wrong.
I migrated the data from Magento 126.96.36.199 with the migration tool and copied the directory public/media/catalog to pub/media/catalog.
Maybe somebody can help me out, I'm quite new to magento.