An error I do not understand

[codeboy]

I do not know why it happened. My error log is full of it.
I'm using version 5.3.6.

[2018-09-07 10:16:26] Espo.WARNING: E_WARNING: Invalid argument supplied for foreach() {"code":2,"message":"Invalid argument supplied for foreach()","file":"C:\\xampp\\htdocs\\xxx\\application\\Espo\\Core\\Utils\\Database\\Orm\\Converter.php","line":301,"context":{"entityName":"Calendar","entityMetadata":{"collection":{"textFilterFields":["name"],"fullTextSearch":false}},"unmergedFields":["name"],"outputMeta":{"id":{"type":"id","dbType":"varchar"},"name":{"type":"varchar","notStorable":true},"deleted":{"type":"bool","default":false}}}} []

[tanya]

Hi,
do you have any customization, related with Calendar?

[codeboy]

I will check and write.