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I've started with a fresh install of emoncms v8.5.2 on a spare Raspberry Pi v1 running Raspbian Wheezy, empty data folders & new MYSQL database, and worked through the update process to v9.0, so I thought I'd note the process and post it here in case it helps anyone. You may find that on other OS that the update process may differ slightly. 

Whilst in v8, I created two identical 'power' feeds which respectively fed 'kwh' feeds via a 'power to kwh process' and also 'power to kwh/d' feeds. I gave them a suffix of 1 and 2, and created a multigraph comparing both kwh feeds.

I also repeated the whole process of updating from v8.5.2 to the development branch v9.x and got identical results.

The Update Process

This update makes a number of changes to the MYSQL database making it difficult to roll back to v8 once you have updated, so it's probably wise to back up your data folders & MYSQL data before starting.

Stop emonhub & update to v9

sudo service emonhub stop
cd /var/www/emoncms
​git fetch origin
git checkout stable
git pull

Make feedwriter executable:

sudo chown root:root /var/www/emoncms/scripts/feedwriter
sudo chmod 755 /var/www/emoncms/scripts/feedwriter

Create a new settings file:

cp default.settings.php settings.php

Enter your mysql database settings in settings:

nano settings.php

In your browser login to emoncms:

• Check the Administration page - 'Setup > Administration' noting and acting upon any messages reported.
• Update your database - 'Setup > Administration > Update database'.
• Ensure that the correct timezone is selected & saved in 'Setup > My Account'

Flush Redis & start emonhub

redis-cli flushall
sudo service emonhub start

Your inputs & feeds should now start updating, and you should again check the Administration page and deal with any messages reported in there.

Feed Errors

If you check your power to kWh feeds, you may see that the value has dropped during the update. This is a bug in v9.0 hopefully to be resolved.

To correct the error, you will need to recalculate the kWh data by using a script.

First, stop emonhub

sudo service emonhub stop

Install and run the script:

cd && sudo git clone https://github.com/emoncms/usefulscripts.git
sudo php usefulscripts/process/power_to_kwh.php

Answer the questions when prompted, choosing to overwrite the existing kWh feed. Repeat this for all of your affected kWh feeds.

Please note that entering a value for the kWh feed interval period is compulsory and although I chose 10 (seconds) in this example, you may find that 300 is more appropriate for this type of feed. i.e don't leave it blank!  I would assume the same for "set max power level" so enter a value in there too.

Flush Redis & start emonhub

redis-cli flushall
sudo service emonhub start

As you can see above, the script has rebuilt the FINA kwh1 data from my FIWA kwh source feed, whilst the kwh2 feed still shows the drop. I've since run the script on the kwh2 feed an that too is now fine.

If you have the 'app' module installed, you will also need to update that to v9 as follows:

cd /var/www/emoncms/Modules/apps
git checkout 9.0
git pull

If you are using the 'notify' module, see the mod by Jumpmaster to ensure it also works under v9.

It's probably worth mentioning than when you install/update to v9, a number of scripts will also be available to you to make some of the other tasks easier, such as installing a USB HDD. Please see the Raspberry Pi initial installation guides for more details.

Paul