Token error when editing products

[Germont]

I edit products, and after saving, once in a while I get this error on a white screen. It happens only on LS.

/admin/index.php?route=catalog/product/edit&user_token=Vd8vKvlITmnAxnjSNK81zlMPYbVjGBJi&product_id=23038

Therefore, during working hours I must switch to Apache so the owners can do their job.

 

[Germont]

It was my fault. I mounted /public_html/system/storage/cache/ into a tmpfs partition, but somehow a few remnant sub-directories had only root ownership. I should have deleted those directories.