https://musicbrainz.org/event/9dc6b52e-82cf-41a0-bdeb-7f4818d7623c gives:

TypeError: Cannot read properties of undefined (reading 'replace') at g (/home/musicbrainz/musicbrainz-server/root/static/build/server.js:1:361587) at b (/home/musicbrainz/musicbrainz-server/root/static/build/server.js:1:362396) at w (/home/musicbrainz/musicbrainz-server/root/static/build/server.js:1:363157) at zb (/home/musicbrainz/musicbrainz-server/node_modules/react-dom/cjs/react-dom-server-legacy.node.production.min.js:63:195) at Cb (/home/musicbrainz/musicbrainz-server/node_modules/react-dom/cjs/react-dom-server-legacy.node.production.min.js:66:254) at W (/home/musicbrainz/musicbrainz-server/node_modules/react-dom/cjs/react-dom-server-legacy.node.production.min.js:72:89) at Cb (/home/musicbrainz/musicbrainz-server/node_modules/react-dom/cjs/react-dom-server-legacy.node.production.min.js:70:13) at W (/home/musicbrainz/musicbrainz-server/node_modules/react-dom/cjs/react-dom-server-legacy.node.production.min.js:72:89) at Cb (/home/musicbrainz/musicbrainz-server/node_modules/react-dom/cjs/react-dom-server-legacy.node.production.min.js:70:13) at W (/home/musicbrainz/musicbrainz-server/node_modules/react-dom/cjs/react-dom-server-legacy.node.production.min.js:72:89)

Apparently a new issue after a setlist change, so probably due to problems in the way we process the setlist?

Reported on support email.