Norway conducted trials of Internet voting in 2011 and 2013.
Internet voting was discontinued after the trials found no improvement in turnout (including no increase in youth turnout), combined with security concerns.
An archive of reports in Norwegian and English is available: The e-vote trial.
Here are some highlights of the reports:
Evaluation of the e-voting trial in 2011 – English summary of Institutt for Samfunnsforskning (ISF) report
we find no evidence that groups of voters have been mobilized to take part in the election as a result of internet voting.
The analyses, in sum, indicate that the trial did not have an effect on voter turnout.
young voters prefer to walk to the polling station on Election Day. They defined traditional voting as a symbolic and ceremonial act that indicates adultness.
Evaluation of the e-voting trial in 2013 (PDF) – English text begins on p 135 (p 137 in PDF)
In line with previous research, our findings indicate that the trial with internet voting does not lead to increased turnout in elections.
The government announced in 2014 that Internet voting trials would be discontinued.
June 25, 2014 – Internet voting pilot to be discontinued
As there is no broad political desire to introduce internet voting, the Government has concluded that it will would be inappropriate to spend time and money on further pilot projects.
The Institute for Social Research evaluated the pilot project in 2013… The report shows that the voters have limited knowledge about the security mechanisms in the system.
“This shows how important it is that elections are conducted at polling stations where election officials make sure that the principle of free and fair elections and the secrecy of the vote is respected,” says [Minister of Local Government and Modernisation Jan Tore] Sanner.
In Norwegian – Ikke flere forsøk med stemmegivning over Internett
The BBC reported this as E-voting experiments end in Norway amid security fears.
As part of the project, in 2009 there was a report on security. It notes the added risks from remote voting.
The system is no longer by necessity confined to the local polling station; conceivably it is accessible world-wide, thus increasing the potential number of attackers and attack vectors dramatically.
Also as part of the project, in 2012 there was 196-page report International Experience with E-Voting [with a focus on Internet Voting] (PDF).