OCSP Request failed with following message

Recently I’m receiving the following error message from Let’s Encrypt’s OCSP end point. The error does not seem specific to the request content (i.e, the certificate) since the error does not recur upon a second attempt.
Error message :

“An error occurred while processing your request.
Reference #102.3dd91002.1515855601.40f441d3”

Multiple reference numbers were received for other occurrences of this error message. Let me know if you want those numbers too.

The above error occurred for Certificate with Serial No. : 04:d5:ef:e2:6c:0e:d4:4a:93:3d:f6:1d:0a:ca:44:64:a2:b5

Request Time: Sat Jan 13 16:00 CET 2018 ( +1 GMT )

Sanjaykumar M

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Hi Sanjaykumar,

Could you describe what tool or command you’re using to make the OCSP query?

@cpu, could you also take a look at this?

I’m using Java based client for the OCSP query using BouncyCastle API. Do you want the snippet ?

Yes, please, it would be good to see as much as possible about how the request was made.

import org.bouncycastle.asn1.DEROctetString;
import org.bouncycastle.asn1.ocsp.OCSPObjectIdentifiers;
import org.bouncycastle.asn1.x509.Extension;
import org.bouncycastle.asn1.x509.Extensions;
import org.bouncycastle.cert.jcajce.JcaX509CertificateHolder;
import org.bouncycastle.cert.ocsp.CertificateID;
import org.bouncycastle.cert.ocsp.OCSPException;
import org.bouncycastle.cert.ocsp.OCSPReq;
import org.bouncycastle.cert.ocsp.OCSPReqBuilder;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.operator.OperatorException;
import org.bouncycastle.operator.jcajce.JcaDigestCalculatorProviderBuilder;

//issuerCert -> java.security.cert.X509Certificate
//serialNumber -> java.security.cert.X509Certificate leafCertificate.getSerialNumber();

//Add provider BC
Security.addProvider(new BouncyCastleProvider());
// Generate the id for the certificate we are looking for
CertificateID certificateId = new CertificateID(
    new JcaDigestCalculatorProviderBuilder().build().get(CertificateID.HASH_SHA1),
    new JcaX509CertificateHolder(issuerCert), serialNumber);
// basic request generation with nonce
OCSPReqBuilder gen = new OCSPReqBuilder();	
BigInteger nonce = BigInteger.valueOf(System.currentTimeMillis());
Extension ext = new Extension(OCSPObjectIdentifiers.id_pkix_ocsp_nonce, false, new 
gen.setRequestExtensions(new Extensions(new Extension[]{ext}));

OCSPRequest ocspRequest = gen.build();
byte[] requestData = ocspRequest.getEncoded();

The above is the snippet that generates the request body which is written to the outputstream while connecting to Let’s Encrypt’s OCSP end point.

I doubt if the client has anything to do with the error I’ve reported, since the error does not occur for all requests that I submit, only a small fraction of requests fail.

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I doubt if the client has anything to do with the error I’ve reported, since the error does not occur for all requests that I submit, only a small fraction of requests fail.

Let me jump in here, because I think we are seeing the same thing happen and I suspect it’s a network issue.

We have an openresty which is generating this log line a few thousand times a day: "[…] failed to get ocsp response: OCSP responder returns bad HTTP status code (http://ocsp.int-x3.letsencrypt.org): 503, context: […]"
The (vast) majority of requests is OK (HTTP 200) but since normal returns do not get logged, I have no idea what the actual ratio is :frowning:

When trying to debug this by hand, it does not take too many tries to get the 503:

# openssl ocsp -issuer chain.pem -cert cert.pem -VAfile chain.pem -text -no_nonce -header Host ocsp.int-x3.letsencrypt.org -url http://ocsp.int-x3.letsencrypt.org
Error querying OCSP responsder
140006291846816:error:27076072:OCSP routines:PARSE_HTTP_LINE1:server response error:ocsp_ht.c:250:Code=503,Reason=Service Unavailable

TCP Dump told me, this was send by Akamai (example from an earlier tcpdump):

HTTP/1.1 503 Service Unavailable
Server: AkamaiGHost
Mime-Version: 1.0
Content-Type: text/html
Content-Length: 176
Cache-Control: max-age=0
Expires: Mon, 15 Jan 2018 17:00:58 GMT
Date: Mon, 15 Jan 2018 17:00:58 GMT
Connection: close

An error occurred while processing your request.<p>

From observation, it took a lot more tries to get a 503 for a machine on a different network. This is why I am currently thinking there might be an issue inside or behind Akamai.

I am not sure what to do next. Debugging a CDN from the outside is no fun :wink:

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I can add that I’m having a similar issue.

In Apache’s logs I’ve seen a few:

AH01980: bad response from OCSP server: 503 Service Unavailable

As a client, while loading a website I host, I’ve seen Firefox throw me errors like:

An error occurred during a connection to example.tld. The OCSP server suggests trying again later. Error code: SEC_ERROR_OCSP_TRY_SERVER_LATER

Reloading the page works. I’ve tried verifying manually using openssl but haven’t been able to provoke any errors.

Let’s Encrypt Ops here. We have a ticket open with Akamai and are working to pin down why this is happening. We’ll update with new information and may request a curl or similar if it looks like that would help.

Thanks for posting the errors you are seeing.


Hey there,
got similiar Problems here with Apache. Hundreds of those Errors today:

[Wed Jan 17 15:46:19.043118 2018] [ssl:error] [pid 16026] [client] AH01980: bad response from OCSP server: 503 Service Unavailable

If more Infos are needed just drop me a Line.

Andreas Schnederle-Wagner

@isk - got any news for us on this?

[Thu Jan 18 10:22:14.401474 2018] [ssl:error] [pid 26810] [client] AH01980: bad response from OCSP server: 503 Service Unavailable
[Thu Jan 18 10:22:14.401521 2018] [ssl:error] [pid 26810] AH01941: stapling_renew_response: responder error

We’re chasing it with Akamai, but progress has been slow so far. At this point, the issue seems to be isolated to some of Akamai’s servers in Europe that are having trouble reaching back to our origin servers.

We’re waiting on the results of some research on their side now, but I’ll update here once we know more.


I am facing the issue only in Europe, as you said. US requests seem to be fine.

As this issue is still ongoing, is there a possible workaround, such as adding the IP of a US load balancer in /etc/hosts ?

I have used this workaround previously with full success. However I would guess that it is not totally reliable because the underlying IPs may be rotated by Akamai at any time.

I've included the vantage point from a Google Cloud US POP below:

ocsp.int-x3.letsencrypt.org. 123 IN     CNAME   ocsp.int-x3.letsencrypt.org.edgesuite.net.              
ocsp.int-x3.letsencrypt.org.edgesuite.net. 1513 IN CNAME a771.dscq.akamai.net.                          
a771.dscq.akamai.net.   19      IN      A                                           
a771.dscq.akamai.net.   19      IN      A                                           
ocsp.int-x3.letsencrypt.org. 147 IN     CNAME   ocsp.int-x3.letsencrypt.org.edgesuite.net.              
ocsp.int-x3.letsencrypt.org.edgesuite.net. 3563 IN CNAME a771.dscq.akamai.net.                          
a771.dscq.akamai.net.   19      IN      AAAA    2001:5a0:4402::3ff3:e458                                
a771.dscq.akamai.net.   19      IN      AAAA    2001:5a0:4402::3ff3:e45a                                


Just to add another seeing this issue. Based in the UK, and seeing occasional messages as follows:

[Fri Jan 19 08:52:42.177055 2018] [ssl:error] [pid 12429:tid 139904545642240] [client] AH01980: bad response from OCSP server: 503 Service Unavailable

We’re still in communications with Akamai support. We’ve made a bit of headway and they’re looking into their European regions still. We’ll update again when there’s something major to report.


The issue is that this is knocking people’s website’s “offline” if they have setup Apache2 with it’s default OCSP stapling settings at least on Firefox (Chrome doesn’t do OCSP iirc, so I don’t know how it’ll react). Refreshing multiple times helps of course, since the server will continue to attempt to get a valid response, but the average user will probably resign before that happens.

There is a workaround available here at least if you don’t use the “OCSP Must Staple” extension: OCSP error is taking down my site in firefox

Sadly the error message from Firefox sugggests a server configuration error, which is strictly speaking not quite correct.

There is no information on https://letsencrypt.status.io/ either, which further obfuscates the source of the issue.

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I’m curious.

How is it that a simple restart of Nginx resolves the issue? Because for about a month now, the

2018/01/20 10:42:14 [error] 1620#1620: OCSP responder sent invalid “Content-Type” header: “text/html” while requesting certificate status, responder: ocsp.int-x3.letsencrypt.org

error comes up every weekend (Saturday or Sunday), and I have to restart my nginx for everything to start working, until the next week.

Why does a restart fix it?

Received the same error in US as well on ‘Sun Jan 21 01:23 PST 2018’.

I have the exact same problem on multiple sites.

As more and more virtual sites of an apache server drop out of the stapling cache, these sites are no longer accessible. The only solution I currently see is to temporarily set SSLUseStapling to off.

Please correct me if I am wrong!