I started getting this error recently as well, while making a request to get multiple catalog songs filtered by ISRC (I queried for 25 different codes in a single request, the limit as indicated in the docs). I guess that depending on the amount of data returned by the ISRC lookup, the server times out? and fails with the Gateway Timeout error. Here are the ISRC codes I used, in case anyone wants to try to reproduce it: isrcs = ["USUM71805289", "GBAHS1700199", "USCA21203108", "GBAAA1200728", "GBAHS1600462", "USRC11600201", "USUM71409723", "GBAYE0800265", "USAT21001985", "GBUM71807386", "GBARL1600460", "CAB391100615", "SEUM71401533", "GBHMU1500070", "USWB10002407", "USVR19600010", "USUM71800463", "USUM71703825", "USUM71311296", "USUM71211793", "USSM11703300", "GB28K1100030", "GB28K1700019", "USCM51300762", "USWB10300474"] This is the amount of nodes each ISRC returned: {"USUM71805289"=>7, "USCA21203108"=>44, "GBAHS1700199"=>7, "GBUM71807386"=>72, "GBAHS1600462"=>33, "USAT21001985"=>101, "USRC11600201"=>4, "GBAYE0800265"=>88, "GBAAA1200728"=>28, "USUM71409723"=>12, "GBARL1600460"=>2, "USUM71703825"=>129, "USUM71311296"=>72, "USUM71800463"=>87, "USUM71211793"=>16, "USWB10002407"=>41, "CAB391100615"=>4, "GBHMU1500070"=>4, "USVR19600010"=>18, "SEUM71401533"=>76, "USSM11703300"=>1, "GB28K1100030"=>4, "GB28K1700019"=>1, "USWB10300474"=>17}

Hi, I came here to report that I'm also having this issue. Here's an example of a request payload that fails with "Unable to update tracks" and a response code of 500: {"data":[{"id":"1231174877","type":"songs"},{"id":"1643544720","type":"songs"}]} An inconvenient side effect from this is that when you include a song ID that usually goes through, you get no errors or messages back indicating that other songs didn't make it. This makes it difficult to handle errors and take the appropriate actions.

I just had this issue after removing the sim card. Turns out that Wifi was still "on" but somehow the iPhone got into a SOS mode only. The fix: Go to settings, turn off wifi, turn it back on. Try to load a webpage in Safari and, if it works, try signing off of iCloud again. If that doesn't work, try restarting your phone.