Sorry for my tone.

I have found in this forum tons of explanations about why file transfers is limited to 48k.

Reasons given so far is:

• php configurations:
  
  • max post size
  • max upload size
• apache configuration:
  
  • LimitRequestBody (which I never saw set in a server by default)
• for your security
• and even dumbness of the user

However every time the subject is brought on the real answer is dodge and ignored.
A simple, I^Bwe don't know would be better to get other people helping.

That said the real limitation is in mysql.

The field type BLOB has a limit of 64k - 1, which converted to base64 gives the magic number of 48k.

So, if you understand what you are doing, just change it from BLOB to LONGBLOB.