PayPal REST API: Requesting oauth token returns 500 - paypal

Question

Two days ago, something broke with our paypal integration. Unfortunately, trying to contact paypal support has proven to be of no help (no reply in 2 days), so I'll try my luck, here.
Requesting the token (curl https://api.paypal.com/v1/oauth2/token -H "Accept: application/json" -H "Accept-Language: en_US" -u "****:****" -d "grant_type=client_credentials") started ALWAYS returning an empty response and well, a 500 error.
Note that the same works just fine with api.sandbox.paypal.com and sandbox credentials.
I double checked our credentials and they are fine. Note as well, that it doesn't matter what credentials I use, it always returns the same - 500.
Here's the output of curl ... -v; looks like you have an internal server error, as the 500 shows:
* About to connect() to api.paypal.com port 443 (#0)
* Trying 173.0.88.98...
* connected
* Connected to api.paypal.com (173.0.88.98) port 443 (#0)
* successfully set certificate verify locations:
* CAfile: /usr/ssl/certs/ca-bundle.crt
CApath: none
* SSLv3, TLS handshake, Client hello (1):
* SSLv3, TLS handshake, Server hello (2):
* SSLv3, TLS handshake, CERT (11):
* SSLv3, TLS handshake, Request CERT (13):
* SSLv3, TLS handshake, Server finished (14):
* SSLv3, TLS handshake, CERT (11):
* SSLv3, TLS handshake, Client key exchange (16):
* SSLv3, TLS change cipher, Client hello (1):
* SSLv3, TLS handshake, Finished (20):
* SSLv3, TLS change cipher, Client hello (1):
* SSLv3, TLS handshake, Finished (20):
* SSL connection using DES-CBC3-SHA
* Server certificate:
* subject: C=US; ST=California; L=San Jose; O=PayPal, Inc.; OU=PayPal Production; CN=api.paypal.com
* start date: 201
* expire date: 201
* subjectAltName: api.paypal.com matched
* issuer: C=U
* SSL certificate verify ok.
* Server auth using Basic with user '****'
> POST /v1/oauth2/token HTTP/1.1
> Authorization: Basic ****
> User-Agent: curl/7.27.0
> Host: api.paypal.com
> Accept: application/json
> Accept-Language: en_US
> Content-Length: 29
> Content-Type: application/x-www-form-urlencoded
>
* upload completely sent off: 29 out of 29 bytes
* additional stuff not fine /usr/src/ports/curl/curl-7.27.0-1/src/curl-7.27.0/lib/transfer.c:1037: 0 0
* HTTP 1.1 or later with persistent connection, pipelining supported
< HTTP/1.1 500 Internal Server Error
< Server: Apache-Coyote/1.1
< Date: Thu, 28 Mar 2013 15:59:53 GMT
< Content-Length: 0
< Connection: close
<
* Closing connection #0
* SSLv3, TLS alert, Client hello (1):
Thanks!

Answer 1

This is something that is currently being looked into. If you have not already opened a ticket with PayPal MTS I would advise opening up a ticket with Technical Support, so that your issue can be added to the examples. You will also then be notified once the issue has been resolved.
edit: This is now resolved as of 04:12 AM GMT (31/03/2013).