What can I do about this error?
Neither TortoiseSVN nor svn will let me do that.
PS F:\usr\Proj\cbDevel328WrkCC> cd .\trunk\
PS F:\usr\Proj\cbDevel328WrkCC\trunk> svn delete FortranProject
svn: E200005: Use --force to override this restriction (local modifications may be lost)
svn: E200005: 'F:\usr\Proj\cbDevel328WrkCC\trunk\FortranProject' is not under version control
PS F:\usr\Proj\cbDevel328WrkCC\trunk>
And a clean update gets the error.
PS F:\usr\Proj\cbDevel328WrkCC\trunk> svn update
Updating '.':
Fetching external item into 'src\plugins\contrib\FortranProject':
svn: warning: W155035: The external 'https://svn.code.sf.net/p/fortranproject/code/trunk' defined in svn:externals at 'F:\usr\Proj\cbDevel328WrkCC\trunk\src\plugins\contrib' cannot be checked out because 'F:\usr\Proj\cbDevel328WrkCC\trunk\src\plugins\contrib\FortranProject' is already a versioned path.
At revision 13804.
svn: E205011: Failure occurred processing one or more externals definitions
PS F:\usr\Proj\cbDevel328WrkCC\trunk>
Even using --force does not work.
PS F:\usr\Proj\cbDevel328WrkCC\trunk> svn delete FortranProject --force
svn: E125001: 'F:\usr\Proj\cbDevel328WrkCC\trunk\FortranProject' does not exist
PS F:\usr\Proj\cbDevel328WrkCC\trunk> svn update
Updating '.':
Fetching external item into 'src\plugins\contrib\FortranProject':
svn: warning: W155035: The external 'https://svn.code.sf.net/p/fortranproject/code/trunk' defined in svn:externals at 'F:\usr\Proj\cbDevel328WrkCC\trunk\src\plugins\contrib' cannot be checked out because 'F:\usr\Proj\cbDevel328WrkCC\trunk\src\plugins\contrib\FortranProject' is already a versioned path.
At revision 13804.
svn: E205011: Failure occurred processing one or more externals definitions
PS F:\usr\Proj\cbDevel328WrkCC\trunk>