{"record":{"id":"6314e4a7c4d6cbf0","repo":"apache/hadoop","slug":"failed-to-obtain-user-group-information","errorCode":null,"errorMessage":"Failed to obtain user group information: {}","messagePattern":"Failed to obtain user group information: (.+?)","errorType":"exception","errorClass":"SecurityException","httpStatus":null,"severity":"error","filePath":"hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/UserProvider.java","lineNumber":50,"sourceCode":"import org.apache.hadoop.security.UserGroupInformation.AuthenticationMethod;\n\n/** Inject user information to http operations. */\n@Provider\npublic class UserProvider implements Supplier<UserGroupInformation> {\n  @Context\n  private HttpServletRequest request;\n\n  @Context\n  private ServletContext servletcontext;\n\n  public UserGroupInformation get() {\n    final Configuration conf = (Configuration) servletcontext\n        .getAttribute(JspHelper.CURRENT_CONF);\n    try {\n      return JspHelper.getUGI(servletcontext, request, conf,\n          AuthenticationMethod.KERBEROS, false);\n    } catch (IOException e) {\n      throw new SecurityException(\n          SecurityUtil.FAILED_TO_GET_UGI_MSG_HEADER + \" \" + e, e);\n    }\n  }\n}","sourceCodeStart":32,"sourceCodeEnd":54,"githubUrl":"https://github.com/apache/hadoop/blob/2add9630210752f88ceb1bb74eb65e37bf41da8e/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/web/resources/UserProvider.java#L32-L54","documentation":"UserProvider is the JAX-RS injection supplier that gives WebHDFS/HttpFS resource classes a UserGroupInformation for the current HTTP request. get() calls JspHelper.getUGI(servletcontext, request, conf, KERBEROS, false); when that throws IOException (SPNEGO/Kerberos failure, bad delegation token, proxy rules) it is rethrown as SecurityException prefixed with SecurityUtil.FAILED_TO_GET_UGI_MSG_HEADER (\"Failed to obtain user group information:\"). The real reason is the chained IOException.","triggerScenarios":"A WebHDFS or HttpFS HTTP request whose authentication fails: expired or absent TGT/keytab on the server, SPNEGO principal misconfiguration, a delegation token that expired or predates a NameNode restart (fresh secret manager), Kerberos clock skew, or disallowed proxyuser impersonation.","commonSituations":"curl/WebHDFS clients with SPNEGO after TGT expiry; schedulers (Oozie/jobs) holding delegation tokens issued before a restart without persistent token manager config; secure clusters after changes to dfs.namenode.kerberos.* or hadoop.http.authentication.*; NTP drift on the KDC or NameNode.","solutions":["Read the NameNode/HttpFS server log for the underlying IOException — the SecurityException message only prefixes it","Refresh credentials: kinit again on the client, or restart the daemon with a valid keytab, then retry","If using delegation tokens, fetch a fresh one (webhdfs op=GETDELEGATIONTOKEN) or renew before expiry","Verify SPNEGO setup: dfs.namenode.kerberos.internal-spnego-principal / HTTP/_HOST@REALM and a valid krb5.conf on the server","Check hadoop.proxyuser.* mappings when the request impersonates another user"],"exampleFix":"// before: fire request once and crash on SecurityException\nResponse r = webhdfs.path(\"/data\").queryParam(\"op\", \"OPEN\").request().get();\n\n// after: catch, re-login from keytab, retry once\ntry {\n  return webhdfs.path(\"/data\").queryParam(\"op\", \"OPEN\").request().get();\n} catch (SecurityException e) {\n  UserGroupInformation.getLoginUser().checkTGTAndReloginFromKeytab();\n  return webhdfs.path(\"/data\").queryParam(\"op\", \"OPEN\").request().get();\n}","handlingStrategy":"retry","validationCode":"UserGroupInformation ugi = UserGroupInformation.getLoginUser();\nugi.checkTGTAndReloginFromKeytab(); // refresh TGT/keytab before the request","typeGuard":null,"tryCatchPattern":"try {\n  return callWebHdfs();\n} catch (SecurityException e) {\n  if (!e.getMessage().startsWith(SecurityUtil.FAILED_TO_GET_UGI_MSG_HEADER)) throw e;\n  UserGroupInformation.getLoginUser().checkTGTAndReloginFromKeytab();\n  return callWebHdfs(); // one retry after credential refresh\n}","preventionTips":["Run long-lived clients and daemons with keytabs plus automatic relogin","Renew delegation tokens before expiry; refetch after cluster restarts","Keep KDC, NameNode, and client clocks NTP-synced","Always check the server log for the underlying IOException"],"tags":["kerberos","spnego","webhdfs","authentication","hdfs","security"],"backgroundTag":"kerberos-authentication-failure","analyzedSha":"2add9630210752f88ceb1bb74eb65e37bf41da8e","analyzedAt":"2026-08-22T19:55:07.957Z","schemaVersion":2},"datasetVersion":"2026-08-22T20:17:22.307Z"}