Update from 3.8.0 to current - PHP 7

[dugjohnson]

I need to move a client from 3.8.0 to current. When I try to update, I get error saying PHP Fatal error: Uncaught TypeError: Argument 1 passed to Monolog\ErrorHandler: handleException() must be an instance of Exception, instance of Error given....
This is also true for a rebuild.
I have just updated a client's server to Ubuntu 16.10. They have been running on PHP 7 before the upgrade.
I'm guessing that PHP 7 has been non-compatible with this aspect of the program for a long time, but because everything was working and nobody tried to update, nobody noticed.

I see several options...maybe there is a better one?
1) Can I install the latest version of Espo and then, somehow, transition the databases from version 3.8 to current? This would be my best option, if Espo can update the databases with just a change of source code.
2) Can I update the exception handler only, so that I can get through the rebuild and upgrade process?
3) Do I have to drop back to version 5.? of PHP and then move back to PHP7 after doing the update.
4) Something else?

[iscon]

If I were you I'd be setting up an older Ubuntu version locally - do the upgrade there and then transfer it back to the production server. I trust you still have the original 3.8. With the 4.x versions there is no problem with php7. Nonetheless we are using 5.6 on Ubuntu 16.04 for other reasons. This is actually quite easy to install and is a good compromise.

[tanya]

The easiest way is to downgrade php version 5.(5+)
Because the first option require too many manipulations (possible in the future will be written a guide for manually upgrade with file replacing)

[dugjohnson]

Thank you both. I downloaded to a VM, which I took back to PHP5.6, did all of the updates there, then put it back on the prod server. I am staying with 7.0 there. Again, thanks.