Why am I getting "⚠ cannot concatenate 'str' and 'NoneType' objects" for every sample log file I try to import into Splunk?

[dweston1]

Every sample log file that I attempt to import as my data source returns the exception:

 ⚠ cannot concatenate 'str' and 'NoneType' objects 

Even the sample log files from Buttercup Games.

[rickmeister]

Having the same problem with a brand new test splunk trial and the tutorial data and no additional apps installed.

[davidmiko]

I had been struggling with this issue, and through some trial and error determined that it was an add-on app that I had recently installed. Try disabling any apps that you have recently installed, you might find this to be the solution to your problem as well!

[ldongradi_SPL]

I downvoted this post because the error is not related to an app but to the .csv file format