new category goes to http 500 error

Hi, when I making a new category, save it, then I want to go beck to edit, it goes to a blank page with a http 500 error message. When I attach one of my product to this category during editing the product, it occur the same error. I checked the database with phpmyadmin, everything is looking ok with the category tables.(There is no duplicated id numbers as far as i suppose) Meanwhile, in the frontend, I can choose that category on the extended search tab, so it seems to live.
with or without seo link, the same. On the error log I can not find anything, although probably I looking in a wrong log file.
Where should I try to find the answer?

First of all, you should either look into error log or enable error reporting to see the actual error instead of generic error 500.

thekrotek wrote: ↑

Mon Sep 18, 2017 7:21 am

First of all, you should either look into error log or enable error reporting to see the actual error instead of generic error 500.

How can I do it? on the admin/settings/server/maintance mode is on. How can I see the logs?

tkk wrote: ↑

Mon Sep 18, 2017 2:18 pm

thekrotek wrote: ↑

Mon Sep 18, 2017 7:21 am

First of all, you should either look into error log or enable error reporting to see the actual error instead of generic error 500.

How can I do it? on the admin/settings/server/maintance mode is on. How can I see the logs?

The logs are in System > Tools > Error Log

Well, this is the last few line of my error log. Today morning I tried to edit that new category (8:16), and at 13:40 as well.

"/var/www/clients/client21/web180/web/system/library/db/mysqli.php on line 18
2017-09-18 8:16:17 - PHP Warning: mysqli::query(): (21000/1242): Subquery returns more than 1 row in /var/www/clients/client21/web180/web/system/library/db/mysqli.php on line 18
2017-09-18 8:16:19 - PHP Warning: mysqli::query(): (21000/1242): Subquery returns more than 1 row in /var/www/clients/client21/web180/web/system/library/db/mysqli.php on line 18
2017-09-18 13:40:23 - PHP Warning: mysqli::query(): (21000/1242): Subquery returns more than 1 row in /var/www/clients/client21/web180/web/system/library/db/mysqli.php on line 18
"

I solved the problem with this hint:
https://github.com/opencart/opencart/issues/1632

There was more lines in the url_alias table with the same category id somehow. I deleted these rows, and everything is going well.