The nightly build failed and a bug was assigned to me. Digging trough the msbuild.log file the error was in the deployment

One or more tasks did not complete before the timeout was reached. We waited 10.1 minutes for the tasks to complete.
build.log

There is a timeout of 10 minutes? Never knew this. To be precise, the timeout is in octo.exe not in the EXEC task of msbuild (which has no default timeout).

In the octopus deploy task log we read the deployment had succeeded in 11 minutes. Took 1 minute too long 😕

This task started 14 hours ago and ran for 11 minutes
Octopus deploy task summary

In the octopus documentation we found the deploymenttimeout parameter that has a default of 00:10:00. Looks like we found the solution. We must specify the deploymenttimeout from more that 11 minutes.

Octo.exe create-release --server=http://our.octopus.server/api 
  --project="slow deployment" --deployto=Development 
  --apikey=API-123456789 --waitfordeployment 
  --enableservicemessages --deploymenttimeout=00:30:00