症状

The following error(s) is reported, while writing to SVN repository;

svn: attempt to write a readonly database

And,

svn: OPTIONS of 'http://192.178.30.86/example': authorization failed: Could not authenticate to server:
rejected Basic challenge (http://192.178.30.86)

原因

The Apache server doesn't have file permissions to read/write to the Subversion Database files (*.db).

ソリューション

Change read/write permissions on the .db files, so that Apache can access them properly.