Edit attribute produce 500 error

Question

I have a lot of custom attributes but one of them is not editable via Magento backend anymore. It gives 500 error on edit and server logs says:

AH01797: client denied by server configuration: /.../app/etc/local.xml

Could not find a solution for it yet. Any suggestions?

EDIT

It seems that the real error is caused by a memory limit problem:

[19-Jun-2017 07:35:04 UTC] PHP Fatal error: Allowed memory size of 268435456 bytes exhausted (tried to allocate 85 bytes) in /.../lib/Zend/Db/Statement/Pdo.php on line 291

So I will check the database, maybe there are too many attributes or something like this. If that does not work I could try to increase the memory limit, but I think I will check the database first.

EDIT2

I have checked the database and the memory limit:

The memory limit is set to 256M and I think that's ok or do you think I should increase this?

Furthermore, I have seen that the table eav_attribute_option contains 459465 entries. So I have checked this table and this is the result:

COUNT(option_id) | attribute_id
2 |18
28 | 177
34158 | 185
218 | 186
425059 | 188

The attributes with id 185 and 188 contain a lot of options. So I have checked this and the attribute with id 188 is the attribute which produces the 500 error. This attribute is called 'color_frontend' and contains some color options like black, blue and so on, but the sum of this colors will not reach the count of 425059. So I will check the import script which imports product data and adds this options. There must be an issue with the add option function.

Answer 1

I have seen that the table eav_attribute_option contains 459465 entries. So I have checked this table and this is the result:

COUNT(option_id) | attribute_id
2 |18
28 | 177
34158 | 185
218 | 186
425059 | 188

The attributes with id 185 and 188 contain a lot of options. So I have checked this and the attribute with id 188 is the attribute which produces the 500 error. This attribute is called 'color_frontend' and contains some color options like black, blue and so on, but the sum of this colors will not reach the count of 425059. So I will check the import script which imports product data and adds this options. There must be an issue with the add option function.

So I think the question is answered, the 500 error is caused by a huge eav_attribute_option table and could be fixed by increasing the memory limit or in my case by solving the import error, but I think the import function problem should be a new question.