Tried today, but this time the page loaded, so it will have to wait until next time.
I do see a lot of errors in the console on this run:
GET http://_buildserver_/blue/rest/organizations/jenkins/pipelines/trunk-functional-matrix/pipelines/os=centos%20%7C%7C%20release-centos,test=lib/pipelines/case/pipelines/search_unsorted 404 (Not Found)
Unhandled Rejection: TypeError: Cannot read property 'self' of undefined
at ActivityService.bunkerKey (blueocean.js:5616)
at ActivityService.setItem (blueocean.js:5659)
at executeAction (blueocean.js:103343)
at ActivityService.res (blueocean.js:103315)
Unhandled Rejection: TypeError: Already read
That said though, that original stack trace seems diagnosable because it's essentially an NPE. Each level in the stack just has to decide whether a null object is valid or not, and bam, you know where the problem is.