Hi

As per knowledge base article  68836 there are changes in windows standards, any file from 2013 or older can not directly convert to 2016, they are require to convert to 2014 or 2015 first before converting to 2016.

As for file will not convert by copying over network but flash drive work.  That could be few possible, server connection manager not upgraded; Saj folder that was copy across the network did not copy correctly (Missing file or damage file), can try copy a .cab backup and test it.  

Thanks for that but the problem is that it won't convert in 2015 either. We first tried to update the data with 2015 and it wouldn't work and then we tried on 2016 it wouldn't work either. The server connection manager is fully updated and running properly and as far as the saj folder being corrupt i have tested that theory to no avail. I copied the network copy onto my local machine and it upgraded just fine. That said we thought it was a firewall issue but we turned off the firewall and antivirus and still it would not work.

A side note though even though sage says you can't update pre 2014 files with the 2016 version its not true. You can still update them right from 2016 you just need to make sure 2015 is also installed. I have done this many times on my laptop and it saves you from upgrading in the 2015 version and then having to open 2016.

Actually it was my bad, I was trying to say it require 2014 or 2015 installed to able to upgrade to 2016 directly (KB does suggest that)

From my experience conversion issue comes with data or environment issues.  if you are able to convert other files, that mean environment is good.  which left to database itself.  Normally database issue can be partially converted (if conversion fail, normally it create a conversion log in saj folder, it is time stamp text file i.e. 2015-10-30-01-12-05.txt) then I would suggest try to find a backup that doesn't contain that log;   then I would check if any file in saj have hidden file attribute and open file in original version run advance database check, if all above fail.  You can contact Sage support get them help you upgrade it.