This filename is not safe to use in an URL

Please how do it fix this? i have renamed the file in various ways, and yet i get the same message. It was ok, until i did an update of the component from within Joomla. And since then, we cannot add any file. Below is an example. Thanks

Warning
This filename is not safe to use in an URL: /message/REVFITZGERARDODONKOR_RESURRECTIONLIFE_160417.mp3

First and very important: That message is NOT an error. It is a warning. That means the file was added fine and it should work in most cases. However there may be clients or operating systems which have issues with it, so it's recommended to use a different filename.
In your case, the issue is the capitalised name. Try filenames with are all lowercased and you shouldn't get a warning.
On a sidenote: If you upload the file using the built-in uploader in SermonSpeaker, it should automatically rename the file so it fits the needs.

revfitz_resurrection_life-160417.mp3 is the new filename, but still getting the error. Previous versions worked fine until this update. Clearly the update is not helping

tried internal upload, this is the error.
revfitz_resurrection_life-160417.mp3 (35.5 mb) » Error: COM_SERMONSPEAKER_FU_ERROR_UNABLE_TO_UPLOAD_FILE

If the file can't be uploaded using the internal uploader, then it is likely due to permission issues (not able to write to that directory) or a size limit of the server.

As for the filename, can you try changing the underscores (eg to dashes) as well?
I'm using a Joomla method to check for URL safe characters. It may be that this function is to restrictive.

Anyway, as said it's not an error condition. It's more a "best practice" recommendation.

hello,
Now i have this Franklin.mp3 as a test, since nothing has worked all this while, and yet t get the finename is not safe, so if that is not safe, then what filename again can be safe? i have tried both ways, uploading from within sermonspeaker, and uploading to folder through filemanager.
i have tried installing on different server and different template, and yet, there is a problem.
Something is not right with your recent updates.
i am even using Joomla! 3.5 - 3.6 SermonSpeaker 5.5.4
thanks