BeyondDimension/SteamTools · error · HandleHostsFileException

5

5

Error message

Mark appears multiple [{0}], try resetting the Hosts file or editing the Hosts file and removing the excess Mark and try again

What it means

Thrown by the hosts-file parser when a managed-section delimiter ('mark') is encountered more than once. The application wraps the host entries it owns between start/end mark tokens; 'markLength' is a HashSet tracking marks already seen, and HashSet.Add returning false signals a duplicate. A repeated mark makes the block structure ambiguous, so parsing aborts rather than risking a corrupt rewrite.

Source

Thrown at src/BD.WTTS.Client/Services.Implementation/Net/HostsFileServiceImpl.cs:444

                                    {
                                        backup_datas.TryAdd(bak_line_split_array[1], (bak_line_num, string.Join(' ', bak_line_split_array.ToArray())));
                                    }
                                }
                                return null;
                            }

                            var mark = GetMarkValue(line_split_array);
                            if (mark == null) return true;
                            if (mark == MarkEnd && !markLength.Contains(MarkStart)) return null;
                            if (mark == BackupMarkEnd && !markLength.Contains(BackupMarkStart)) return null;
                            if ((mark == MarkStart || mark == BackupMarkStart) && last_line_value != null && string.IsNullOrWhiteSpace(last_line_value))
                            {
                                var removeLen = last_line_value.Length + Environment.NewLine.Length;
                                stringBuilder.Remove(stringBuilder.Length - removeLen, removeLen);
                            }
                            if (!markLength.Add(mark))
                            {
                                throw new HandleHostsFileException(AppResources.CommunityFix_Hosts_MarkDuplicate_.Format(mark)) { Code = HandleHostsFileException.Code_CommunityFix_Hosts_MarkDuplicate_ };
                            }
                            return null;
                        });
                        if (is_effective_value_v2 != HandleLineResult.Duplicate)
                        {
                            var is_effective_value = Convert(is_effective_value_v2);
                            if (!is_effective_value.HasValue) goto skip;
                            if (!is_effective_value.Value) goto append; // 当前行是无效值，直接写入
                        }
                        string ip, domain;
                        ip = line_split_array[0];
                        domain = line_split_array[1];
                        var match_domain = has_hosts && hosts!.ContainsKey(domain); // 与要修改的项匹配
                        if (markLength.Contains(MarkStart) && !markLength.Contains(MarkEnd)) // 在标记区域内
                        {
                            if (match_domain)
                            {
                                if (isUpdateOrRemove) // 更新值

View on GitHub (pinned to c16ffa08e0)

Solutions

Open the hosts file and delete the duplicated mark line(s) so each mark appears exactly once, then retry.
Reset the hosts file to its default content and let the application rewrite its managed section from scratch.
Check for a second running instance of the app or a conflicting proxy tool writing the same marks, and close it.
Restore the hosts file from a known-good backup before retrying the operation.

Example fix

// before (hosts file has two managed blocks)
# >>> WTTS BEGIN >>>
127.0.0.1 example.com
# <<< WTTS END <<<
# >>> WTTS BEGIN >>>          <- duplicate mark
127.0.0.1 other.com
# <<< WTTS END <<<

// after: keep a single block, remove the duplicate
# >>> WTTS BEGIN >>>
127.0.0.1 example.com
127.0.0.1 other.com
# <<< WTTS END <<<

Defensive patterns

Strategy: validation

Validate before calling

// Before handing the hosts file to the parser, pre-scan for duplicate marks.
bool HasDuplicateMarks(IEnumerable<string> lines, IReadOnlySet<string> markTokens)
{
    var seen = new HashSet<string>();
    foreach (var raw in lines)
    {
        var mark = GetMarkValue(raw.Trim().Split(new[] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries));
        if (mark == null || !markTokens.Contains(mark)) continue;
        if (!seen.Add(mark)) return true; // duplicate
    }
    return false;
}

Try / catch

try { /* parse hosts file */ }
catch (HandleHostsFileException ex) when (ex.Code == HandleHostsFileException.Code_CommunityFix_Hosts_MarkDuplicate_)
{
    // Prompt user to reset the hosts file or auto-remove the duplicate block, then retry once.
    Log.Warning(TAG, $"Duplicate hosts mark: {ex.Message}");
    await OfferHostsResetAsync();
}

Prevention

Always read the existing hosts file and detect existing managed marks before writing, to avoid appending a second block.
Write managed sections atomically (temp file + replace) so a crash never leaves a half-written/duplicated mark.
Use a single owning process; acquire a file lock or mutex before modifying the hosts file.
On startup, validate mark uniqueness and self-heal (keep the first block) instead of throwing.

When it happens

Trigger: Invoking the hosts read/repair routine on a file where a MarkStart/MarkEnd (or BackupMarkStart/BackupMarkEnd) token occurs twice — e.g. after manual editing, a crashed prior write that left a partial block, or two tools each writing their own marks into the same hosts file.

Common situations: User hand-edited the hosts file and duplicated a managed section; a previous process crash left a half-written block; another accelerator/proxy/antivirus tool appended overlapping marks; merging two hosts files by paste.

Related errors

AI-assisted analysis of BeyondDimension/SteamTools@c16ffa08e0 (2026-08-13). Data as JSON: /api/errors/9653cb9bb0baa113. Report an issue: GitHub.