RESOLVED — root cause found, three years later. Leaving a full write-up for anyone who lands here from a search.
Short version: this was never an XO bug, and it was never intermittent. The answer was sitting in the very first test-cli.js output I posted back in May 2023, and I misread it — as did everyone else in this thread, myself very much included.
The line that mattered
failed to bind as CN=Agbasi\, Kismet,...:
80090308: LdapErr: DSID-0C090434, comment: AcceptSecurityContext error, data 569, v4f7c
We all pattern-matched AcceptSecurityContext error to "bad credentials" and moved on. But the meaning is entirely carried by the data field, which is the underlying Win32 status in hex:
data 52e = 0x52E = 1326 = ERROR_LOGON_FAILURE — this is the "wrong password" one
data 525 = 1317 = ERROR_NO_SUCH_USER
data 532 = 1330 = password expired
data 775 = 1909 = account locked out
data 569 = 0x569 = 1385 = ERROR_LOGON_TYPE_NOT_GRANTED
I was getting 569, not 52e. My password was correct all along. AD validated it, then refused the logon type.
Why that happens
xo-server-auth-ldap verifies a password the only way LDAP allows — it re-binds to the directory as the user. Against Active Directory, an LDAP simple bind to a DC is processed as a Type 3 (network) logon on that DC.
So if an account is caught by "Deny access to this computer from the network" (SeDenyNetworkLogonRight) in the Default Domain Controllers Policy (or any other WINNING GPO, for that matter), it cannot complete an LDAP bind — no matter how correct the password is, and no matter which LDAP client is asking.
My environment uses a tiered admin model. Non-domain-admin admin groups are explicitly denied network logon to the DCs. My admin account is in those groups. Hence 569, every single time, by design.
Why it looked intermittent
It wasn't. I sampled it either side of a config change.
I could prove a bind had succeeded recently, because my LDAP-only XO account (no local password on the record at all) minted an API token on 28 July. Then on 31 July I restored RBAC settings on the Default Domain Controllers Policy that had drifted at some
point — I found that during unrelated PKI work. GptTmpl.inf last-write confirms it. The token's last successful use is about eleven hours before that edit.
Two deterministic states, one config change in the middle. That's the whole "intermittency."
My 2023 "seven security groups" theory was wrong
For the record, since it's still up there and someone will find it: I removed group memberships one at a time until auth worked, and concluded there was a membership count limit. There isn't. My own control test disproved it at the time — adding fifteen groups
never reproduced the failure — and I should have taken that seriously instead of filing it under "weird." The variable was never the count. It was which group. One of the removals happened to drop the account out of a denied group.
My other closing theory in this thread — special-character handling in the username or password — was also wrong. Getting 569 back proves AD parsed the escaped DN (CN=Agbasi\, Kismet), found the object, and got as far as evaluating the password. A mangled DN gives you 525 or a DN syntax error, not a logon-rights rejection. ldapts and passport were behaving correctly throughout.
How to check this in 60 seconds
Run the plugin test CLI and note the data value. Convert hex → decimal, look it up in Microsoft's System Error Codes list.
On the DC, look for Security event 4625 with Sub Status 0xC000015B (STATUS_LOGON_TYPE_NOT_GRANTED).
Fastest test of all — from a workstation, as the affected account: net use \\dc01\sysvol. If network logon to the DC is denied, this fails too, and you've confirmed it without touching XO at all.
Check the policy directly:
$p = "\\mydomain.net\SYSVOL\mydomain.net\Policies\{6AC1786C-016F-11D2-945F-00C04fB984F9}" + "\Machine\Microsoft\Windows NT\SecEdit\GptTmpl.inf"
Select-String -Path $p -Pattern "SeDenyNetworkLogonRight|SeNetworkLogonRight"
Resolve the SIDs and see whether your user is in any of the denied groups.
Also worth checking your grant side: if Access this computer from the network doesn't list Authenticated Users directly, ordinary users are probably getting it transitively via Pre-Windows 2000 Compatible Access. Worth confirming before you assume a plain
non-privileged account will work.
What I am NOT doing
Removing those groups from the deny right. It's doing exactly what I rebuilt it to do. Restoring an app login by handing admin groups network access to the DCs for SMB/RPC/LDAP is a bad trade, and I'd just be undoing my own remediation.
Fix
Interim: local XO accounts for the admins who need them. No AD objects created, nothing to unwind later, per-user attribution preserved in the audit log.
Long term: federate XO through Keycloak (OIDC) instead of LDAP. Kerberos ticket issuance is a KDC service operation and is not gated by SeNetworkLogonRight — which is exactly why these accounts log into workstations all day while failing an LDAP bind.
️ Important if you go the Keycloak route: Keycloak's LDAP user federation validates passwords by doing an LDAP bind. Configure it that way and you'll hit data 569 inside Keycloak instead of inside XO and gain nothing. Password validation has to be delegated to
Kerberos/GSSAPI.
This will bite you on anything else you point at LDAP too — Bitwarden, NPM, TrueNAS, the lot. Worth solving once at the IdP.
One request for Vates
@olivierlambert @julien-f — you were right that it was environmental, and I owe you both thanks for the time you put in back in 2023.
That said, there's a real (small) improvement available here. xo-server collapses every auth provider exception into a generic invalid credentials, and the plugin only emits the actual AD error at DEBUG. The DC told us precisely what was wrong on the very first
attempt — it just never reached anywhere a user would look.
Surfacing the LDAP result code and the AD data sub-code at INFO on failure, and in the plugin test output in the UI, would turn this class of problem from a multi-year hunt into a single-session diagnosis. Happy to open an issue on GitHub with the full reproduction if that's useful.
Hope this saves someone else three years. If you found this thread by searching data 569, *ERROR_LOGON_TYPE_NOT_GRANTED**, or "LDAP invalid credentials but password is correct" — check your Deny access to this computer from the network user right first. That's almost certainly it.
