ContentImporter not found during installation of c5.7.3.1

Permalink
I'm attempting to install c5.7.3.1 in a sub directory, but get this error shortly after the database starts to be created:
{"error":{"message":"Class 'Concrete\\Core\\Backup\\ContentImporter' not found"},"errors":["Class 'Concrete\\Core\\Backup\\ContentImporter' not found"]}
Any ideas what's going on?

SkyBlueSofa
 
SkyBlueSofa replied on at Permalink Reply
SkyBlueSofa
I had APC installed. I think this was the issue, but cannot confirm.
SkyBlueSofa replied on at Permalink Reply
SkyBlueSofa
I've run into this issue again in 5.7.4.1.

When I attempt to install c5.7 in a subdirectory, I get this error in the \Concrete\Core\Package\StartingPointPackage\install_permissions() method.

Any suggestions? It seems to me that the Concrete\Core\Backup\ContentImporter isn't being added to the autoloader, but I'm not sure.

Thanks for your help.