Confirming that I'm seeing this issue. This is a problem with the OCLC-hosted EZProxy server. I've filed a support ticket with them.

This issue should now be resolved - I appear to be able to access content again, please let me know if you're seeing any different.

@Samwalton9-WMF Works for me: Oxford Music, JSTOR and Project MUSE are accessible. Thanks!

Works for me, too. Thanks for looking into this so quickly.

@Samwalton9-WMF The problem still seems to be occurring / is occurring again. I have just been able to reproduce it right now.

Confirming I got a down notification at 14:20 UTC. Strangely the Staging service also went down, but has come back up as of 5 minutes ago. I'll ping the support thread again.

Hm, literally as I sent the email production came back up too, having been dow for ~25 minutes. I've flagged this with OCLC anyway.

I can confirm that the error has recurred, but now it is: SEC_ERROR_REUSED_ISSUER_AND_SERIAL

In T365553#9822007, @Aschmidt wrote:

I can confirm that the error has recurred, but now it is: SEC_ERROR_REUSED_ISSUER_AND_SERIAL

I'm not able to reproduce this error. I wonder if you could try clearing cookies for oclc.org and see if that changes anything.

I've deleted oclc cookies, and the error message in Firefox is still the same: SEC_ERROR_REUSED_ISSUER_AND_SERIAL

Firefox can open the library pane, but when I try to open a collection I get this error message.

Any more cookies to delete?

Seems to be a cookie issue, indeed. I've logged in to the library pane with Safari now, and it goes right through to both DeGruyter and Nomos. It's working all right.

Right. I deleted all cookies and cache data in Firefox, logged in again in Wikipedia, Wikipedia Library. And the above error persists in Firefox.

Reports are coming in on our feedback page on German Wikipedia that access to the library has been restored, and I can confirm that it also works for me in Firefox, again. Your help is much appreciated.

I don't know whether I copied something wrong but I get

This page is not available
This page is pending publication, has been removed or moved to a new location

That's on Chrome. I use Edge at home but I'm not there. I will try this afternoon.

In T365553#9826215, @Vchimpanzee wrote:

I don't know whether I copied something wrong but I get

This page is not available
This page is pending publication, has been removed or moved to a new location

That's on Chrome. I use Edge at home but I'm not there. I will try this afternoon.

What URL are you on when you get this error? Is there an associated error message on the page, like SEC_ERROR_REUSED_ISSUER_AND_SERIAL?