Errors in system.log file

[addison74]

This post aims to centralize the errors that occur in the system.log file in production Magento/OpenMage installations.

If there are solutions, please do not hesitate to offer them.

[addison74]

Here are the errors I've kept in this file over time.

2020-08-03T06:12:45+00:00 ERR (3): Notice: iconv_substr(): Detected an illegal character in input string in /home/mydomain/public_html/app/code/core/Mage/Core/Helper/String.php on line 103

2021-03-01T15:33:58+00:00 ERR (3): Notice: Undefined index: hideit in /home/mydomain/public_html/app/code/core/Mage/Contacts/controllers/IndexController.php on line 87

2021-09-21T00:01:31+00:00 ERR (3): Warning: strlen() expects parameter 1 to be string, array given in /home/mydomain/public_html/app/code/core/Mage/Catalog/Model/Layer/Filter/Attribute.php on line 93