Engagement - Troubleshooting Import and File Transfer Activities Failing with 'File Not Found'

The first thing to check in this circumstance is that the file is indeed in the directory of the FTP that the activity is pointing. Once confirmed, there are a few other items to check. If the file has personalization in the naming convention using the time personalization strings the second string (%%Second%%) and minute string (%%Minute%%) have been known to interrupt automations with 'File Not Found' errors for activities working with larger files due to processing time taking longer than one second or one minute.

The suggested practice is to include only the date/time personalization strings necessary to distinguish between files generated by different scheduled runs of the automation.
 
If the automation runs hourly, include down to the hour (ie. FileName%%Year%%%%Month%%%%Day%%%%Hour%%).
If the automation runs daily, include down to the day (ie. FileName%%Year%%%%Month%%%%Day%%).

Generally speaking it is not recommended to use Minute and Second personalization for this purpose. 

Note: Personalization strings used in the File Naming Pattern are case-sensitive.

Timezone Factor:

The automation will be looking for the most recent file closest to your personalization strings (%%Year%%%%Month%%%%Day%%%%Hour%%) and does not process future date files until the system has passed that time. Because of this, the Automation will try to match the file name pattern strings with FTP files based on your account timezone, which can be checked here:

Setup > Settings > Company Settings > Account Settings

If the date and time set on your file is based on your current local timezone and does not match the Account Settings, it may generate the "File Not Found" error as your current local timezone may be ahead of your Account Settings timezone.


Another consideration is, if these failures began occurring in a Marketing Cloud Engagement Business Unit and the activities were previously working, it would be a good idea to check to see if, for the first time an FTP User was created within the Business Unit. You can check this by navigating to:

Business Unit experiencing failure > Setup > Data Management > FTP Accounts

On the right side of the screen there is an "Activity" section and will display if a new FTP User was created. If for the first time in the BU an FTP User was created, this changes the default file location of the Business Unit to the newly created FTP for this account. This means that, to remedy the issue with the automations, you will want to start placing the files in the Business Unit's FTP directory instead of the Enterprise FTP directory as you were previously. 

Whitespace at the beginning or end of a file name are trimmed prior to File Import or Transfer which can cause "File Not Found" errors. Resolution, do not include whitespace characters at the beginning or end of the file name