apache/hadoop · error · IOException

Mount table {mountTableName} has already been configured wit

Error message

Mount table {mountTableName} has already been configured with a merge slash link. A regular link should not be added.

What it means

Error "Mount table {mountTableName} has already been configured with a merge slash link. A regular link should not be added." thrown in apache/hadoop.

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/viewfs/InodeTree.java:697

        // src

        linkType = LinkType.NFLY;
      } else if (src.startsWith(Constants.CONFIG_VIEWFS_LINK_REGEX)) {
        linkEntries.add(
            buildLinkRegexEntry(config, ugi, src, si.getValue()));
        continue;
      } else if (src.startsWith(Constants.CONFIG_VIEWFS_HOMEDIR)) {
        // ignore - we set home dir from config
        continue;
      } else {
        throw new IOException("ViewFs: Cannot initialize: Invalid entry in " +
            "Mount table in config: " + src);
      }

      final String target = si.getValue();
      if (linkType != LinkType.MERGE_SLASH) {
        if (isMergeSlashConfigured) {
          throw new IOException("Mount table " + mountTableName
              + " has already been configured with a merge slash link. "
              + "A regular link should not be added.");
        }
        linkEntries.add(
            new LinkEntry(src, target, linkType, settings, ugi, config));
      } else {
        if (!linkEntries.isEmpty()) {
          throw new IOException("Mount table " + mountTableName
              + " has already been configured with regular links. "
              + "A merge slash link should not be configured.");
        }
        if (isMergeSlashConfigured) {
          throw new IOException("Mount table " + mountTableName
              + " has already been configured with a merge slash link. "
              + "Multiple merge slash links for the same mount table is "
              + "not allowed.");
        }
        isMergeSlashConfigured = true;

View on GitHub (pinned to 2add963021)

Solutions

1. Do not add regular links to a mount table already configured with a merge slash link.
2. Remove either the linkMergeSlash entry or the regular link entries for that mount table in the configuration.

When it happens

Trigger: Thrown during ViewFs mount table initialization when a merge-slash link is added to a mount table that was already configured with a merge slash link; only regular links may follow.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/5c5bb6aedf4f5ce0. Report an issue: GitHub.