Hi Johny,

I’m sorry you are having issues downloading the tz data.

There should have been no changes to access restrictions via user agent or other attributes. I’ll investigate this and get back to you.

Thanks,

James Mitchell

IANA

From: Johny Jose via tz <tz@iana.org>
Reply-To: Johny Jose <johny.jose@oracle.com>
Date: Tuesday, February 3, 2026 at 4:20 PM
To: "tz@iana.org" <tz@iana.org>
Subject: [tz] Downloads from data.iana.org now seem to be sensitive to the User-Agent value supplied in HTTP request headers

Hi,

I am reaching out regarding an issue encountered while attempting to download the latest tzdata release (tzdata2025c.tar.gz) from https://data.iana.org/time-zones/releases/tzdata2025c.tar.gz using Java JDK 8’s HTTP request API. We use the tzupdater tool (https://www.oracle.com/java/technologies/javase/tzupdater-readme.html [oracle.com]) to update the jdk to latest tzdata. Since Monday, January 26, 2026, we have been facing issues while downloading tzdata2025c.tar.gz.

We are receiving an HTTP 403 error response from the server. This appears to be due to a validation failure related to the HTTP header User-Agent (specifically, User-Agent: Java/1.8.0_471). User-Agent values from JDK 11 and later (e.g. User-Agent: Java/11.0.16) do not trigger this issue.

Could you kindly advise on the following:

Has there been a specific format restriction enabled for the User-Agent value string to grant access?

If so, is it possible to whitelist widely used Java-based User-Agent strings?

Error Logs:

sun.net.www.protocol.http.HttpURLConnection sendCONNECTRequest

FINE: sun.net.www.MessageHeader@2f1129655 pairs: {CONNECT data.iana.org:443 HTTP/1.1: null}{User-Agent: Java/1.8.0_471}{Host: data.iana.org}{Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2}{Proxy-Connection: keep-alive}

Jan 30, 2026 8:07:24 AM sun.net.www.protocol.http.HttpURLConnection doTunneling

FINE: sun.net.www.MessageHeader@d4342c21 pairs: {null: HTTP/1.0 200 Connection Established}

Jan 30, 2026 8:07:24 AM sun.net.www.protocol.http.HttpURLConnection writeRequests

FINE: sun.net.www.MessageHeader@770d33265 pairs: {GET /time-zones/releases/tzdata2025c.tar.gz HTTP/1.1: null}{User-Agent: Java/1.8.0_471}{Host: data.iana.org}{Accept: text/html, image/gif, image/jpeg, *; q=.2, */*; q=.2}{Connection: keep-alive}

Jan 30, 2026 8:07:24 AM sun.net.www.http.HttpClient logFinest

FINEST: KeepAlive stream used: https://data.iana.org/time-zones/releases/tzdata2025c.tar.gz

Jan 30, 2026 8:07:24 AM sun.net.www.protocol.http.HttpURLConnection getInputStream0

FINE: sun.net.www.MessageHeader@d4342c211 pairs: {null: HTTP/1.1 403 Forbidden}{Date: Fri, 30 Jan 2026 08:07:24 GMT}{Content-Type: text/plain; charset=UTF-8}{Content-Length: 16}{Connection: keep-alive}{Cache-Control: private, max-age=0, no-store, no-cache, must-revalidate, post-check=0, pre-check=0}{Expires: Thu, 01 Jan 1970 00:00:01 GMT}{Referrer-Policy: same-origin}{X-Frame-Options: SAMEORIGIN}{Server: cloudflare}

java.io.IOException: Server returned HTTP response code: 403 for URL: https://data.iana.org/time-zones/releases/tzdata2025c.tar.gz

I tried to create a new thread in tz - lists.iana.org but could not succeed in it.

Thank you for your assistance. Let me know if you would like any further information.

Thanks,

Johny

Confidential- Oracle Internal