With the patch for DayZ Standalone today to version 1.03 please be aware that most if not all current mods will need to be updated!
Like with all patches, most of the mods that have been released will need to be updated before your server will function properly again. Currently if you have mods on your server that are out of date and broken, after you update the server to 1.02 it will appear to be stuck in a "Loading Phase". To narrow down the out of date mods please refer to your servers RPT files! Being the patch was just released a few hours ago its not likely that every single mod has been updated.
A quick fix for servers with mods that haven't been updated is to simply remove the mods from your launch line until the mods are updated by their developers, at which point you can upload the updated mod back to the server and re-add it to your custom launch parameter!
Once the mods you use have been updated feel free to upload them to your server via FTP and the server should begin to function again!
Please keep an eye on the workshop pages for the mods you run on your server, these pages will be the best source of information as to what issues the mods are having and when they have been updated!
If you are running into any other difficulties, as always please submit a support ticket so we can take a look!