When TimeBasedRollingPolicy fileNamePattern is set to just a file, for example toto-%d{yyyy-MM-dd}-%i.log, then the following code from SizeAndTimeBasedFNATP class fails to detect parent directory and assumes counter = 0 even if there are already ZIP files in the directory. This leads to file name collision during rolling.

void computeCurrentPeriodsHighestCounterValue(final String stemRegex) {
    File file = new File(getCurrentPeriodsFileNameWithoutCompressionSuffix());
    File parentDir = file.getParentFile();

    File[] matchingFileArray = FileFilterUtil.filesInFolderMatchingStemRegex(parentDir, stemRegex);

    if (matchingFileArray == null || matchingFileArray.length == 0) {
        currentPeriodsCounter = 0;
        return;
    }
  ...
}

file.getParentFile() returns null in this case. The workaround is to prefix file name pattern with ./ (./*toto-%d{yyyy-MM-dd}-%i.log). I believe the current working directory should be used as parent directory when parentDir resolves to null.