I think I found a bug thatâs related to the migration. When I try to cross-post my EA Forum post to LessWrong via the âCrosspost to LessWrongâ option, I click the login button only to get:
On Brave (both normal and incognito):
Error: Unexpected token '<', "<!DOCTYPE "... is not valid JSON
On Portable Firefox:
Error: JSON.parse: unexpected character at line 1 column 1 of the JSON data
I asked GPT-5.6 Sol to investigate (I was trying to get it to work, assuming the error was on my side), and it said the following. Following text is generated by it:
That endpoint currently returns an HTTP 404 HTML page beginning with <!DOCTYPE html>, instead of JSON. The equivalent LessWrong endpoint returns valid JSON normally.
The request therefore appears to be intercepted by the new site instead of reaching the legacy ForumMagnum site. ForumMagnum then tries to parse the HTML 404 page as JSON, causing both errors above.
As a check, I sent the same request with prefer_ea_forum_v3=false, which made the endpoint return valid JSON. This seems to confirm that the migration proxy is causing the issue. My suggested fix is to add /^\/api\/v2\/crosspost\// to oldSitePatterns.
I think I found a bug thatâs related to the migration. When I try to cross-post my EA Forum post to LessWrong via the âCrosspost to LessWrongâ option, I click the login button only to get:
On Brave (both normal and incognito):
Error: Unexpected token '<', "<!DOCTYPE "... is not valid JSONOn Portable Firefox:
Error: JSON.parse: unexpected character at line 1 column 1 of the JSON dataI asked GPT-5.6 Sol to investigate (I was trying to get it to work, assuming the error was on my side), and it said the following. Following text is generated by it:
The login button sends a POST request to the EA Forumâs
/api/v2/crosspost/generateTokenendpoint.That endpoint currently returns an HTTP 404 HTML page beginning with
<!DOCTYPE html>, instead of JSON. The equivalent LessWrong endpoint returns valid JSON normally.The likely cause appears to be in the new Forumâs proxy configuration. It routes all
/api/*requests to the new codebase unless they are explicitly listed as old-site routes. However, the new codebase doesnât implement the crossposting API, while ForumMagnum still implements that endpoint.The request therefore appears to be intercepted by the new site instead of reaching the legacy ForumMagnum site. ForumMagnum then tries to parse the HTML 404 page as JSON, causing both errors above.
As a check, I sent the same request with
prefer_ea_forum_v3=false, which made the endpoint return valid JSON. This seems to confirm that the migration proxy is causing the issue. My suggested fix is to add/^\/api\/v2\/crosspost\//tooldSitePatterns.