Upgrade from J3.5.1 fails with white screen

[OldMoldy]

I began the process using Joomla Update component and it never completes.

joomla_update.php log shows:

#
#<?php die('Forbidden.'); ?>
#Date: 2016-08-30 18:42:10 UTC
#Software: Joomla Platform 13.1.0 Stable [ Curiosity ] 24-Apr-2013 00:00 GMT

#Fields: datetime priority clientip category message
2016-08-30T18:42:10+00:00 INFO 96.255.81.117 update COM_JOOMLAUPDATE_UPDATE_LOG_DELETE_FILES
2016-08-30T19:08:04+00:00 INFO 96.255.81.117 update Update started by user Super User (263). Old version is 3.5.1.
2016-08-30T19:08:04+00:00 INFO 96.255.81.117 update Downloading update file from https://github.com/joomla/joomla-cms/re ... ackage.zip.
2016-08-30T19:08:05+00:00 INFO 96.255.81.117 update File Joomla_3.6.0-Stable-Update_Package.zip successfully downloaded.
2016-08-30T19:08:19+00:00 INFO 96.255.81.117 update Starting installation of new version.

[sovainfo]

What were you doing half an hour before the update?

You can't repair a failed update this way, so what happened with the update to 351?

[sozzled]

I began the process using Joomla Update component

Do you know the version of the Joomla Update component that you're using?

...and it never completes.

Some possible reasons why certain processes don't seem to complete include, among others, the amount of available PHP memory, limitations on execution time, insufficient privileges, limitations on upload_max_filesize, the current lunar phase and possibly whether you've paid your electricity account. However (and in all seriousness) you might obtain further information about the cause of your WSOD by changing your error reporting to the maximum setting.

[OldMoldy]

Reran the update attempt after restoring from backup and saw the following message:

Catchable fatal error: Argument 3 passed to JClientFtp::getInstance() must be of the type array, null given, called in /home/truelaw/public_html/libraries/joomla/filesystem/file.php on line 488 and defined in /home/truelaw/public_html/libraries/joomla/client/ftp.php on line 194

[sozzled]

You did not answer my earlier question about the version of Joomla Update that you have installed. Even so, this topic may help: http://forum.joomla.org/viewtopic.php?t=930968

[OldMoldy]

Sorry, I overlooked the question about Joomla Update...ver 2.5.0

[OldMoldy]

After checking the referenced article, I turned off FTP and the update works. I don't see this problem on my other installations on the same VPS server

[sovainfo]

Line 488 should look like: $ftp = JClientFtp::getInstance($FTPOptions['host'], $FTPOptions['port'], array(), $FTPOptions['user'], $FTPOptions['pass']);

Note the , array(), instead of ,,