Traceback (innermost last):
Module ZPublisher.Publish, line 138, in publish
Module ZPublisher.mapply, line 77, in mapply
Module ZPublisher.Publish, line 48, in call_object
Module Products.CMFPlone.controlpanel.browser.quickinstaller, line 213, in call
Module Products.CMFQuickInstallerTool.QuickInstallerTool, line 686, in installProducts
Module Products.CMFQuickInstallerTool.QuickInstallerTool, line 603, in installProduct
Module Products.GenericSetup.tool, line 379, in runAllImportStepsFromProfile
Module Products.GenericSetup.tool, line 1414, in _runImportStepsFromContext
Module Products.GenericSetup.tool, line 1226, in _doRunImportStep
Module Products.CMFPlone.resources.exportimport.bundles, line 28, in combine
Module Products.CMFPlone.resources.browser.combine, line 107, in combine_bundles
Module Products.CMFPlone.resources.browser.combine, line 71, in write_js
Module plone.resource.directory, line 154, in writeFile
Module OFS.Image, line 139, in init
Module OFS.Image, line 535, in _read_data
Module StringIO, line 106, in seek
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 43924: ordinal not in range(128)
I'd suggest to check if you have in your buildout.cfg the pinnings recommanded on Github
If it fails still, try to uninstall the product, update your Plone to the last version and retry.
I don't have test instances for every Plone subversion, but I have one for 5.08 and the product installed fine with the pinnings cited (suprised that you said that it is a 'fresh install' - why install anything else than the current version ? I have never seen anywhere that 5.0.4 was a 'gold' version more highly recommanded than the current one.
Thank you for help. You are right. At the moment of the install, 5.0.4 was the current stable version. My fault, I did'nt know that there was a new one. I'm installing the 5.0.8 with the pinnings cited.