{"id":47549,"date":"2025-04-29T13:58:24","date_gmt":"2025-04-29T17:58:24","guid":{"rendered":"https:\/\/mjtsai.com\/blog\/?p=47549"},"modified":"2026-02-02T10:21:57","modified_gmt":"2026-02-02T15:21:57","slug":"failing-to-finish-updating-macos-on-an-external-disk","status":"publish","type":"post","link":"https:\/\/mjtsai.com\/blog\/2025\/04\/29\/failing-to-finish-updating-macos-on-an-external-disk\/","title":{"rendered":"Failing to Finish Updating macOS on an External Disk"},"content":{"rendered":"<p><a href=\"https:\/\/www.macrumors.com\/2025\/04\/28\/apple-seeds-fourth-beta-of-macos-sequoia-15-5\/\">Juli Clover<\/a>:<\/p>\n<blockquote cite=\"https:\/\/www.macrumors.com\/2025\/04\/28\/apple-seeds-fourth-beta-of-macos-sequoia-15-5\/\">\n<p>Apple today seeded the fourth beta of an upcoming macOS Sequoia 15.5 update to developers for testing purposes, with the software coming a week after Apple released the third  macOS Sequoia  15.5 beta.<\/p>\n<\/blockquote>\n\n<p>My update\/installer\/storage issues continue. I tried updating my external drive several times, but each time when Software Update restarted the Mac it booted from the internal SSD rather than the drive where the update was installed. I don&rsquo;t recall this ever happening before. Each time I tried the update it had to redownload it, and then in failed in the same way. What eventually worked was using Startup Disk to set the external drive as the preferred boot drive.<\/p>\n\n<p>Previously:<\/p>\n<ul>\n<li><a href=\"https:\/\/mjtsai.com\/blog\/2025\/04\/11\/failed-software-update-on-the-external-drive-of-an-apple-silicon-mac\/\">Failed Software Update on the External Drive of an Apple Silicon Mac<\/a><\/li>\n<li><a href=\"https:\/\/mjtsai.com\/blog\/2025\/04\/04\/how-external-bootable-disks-work-with-apple-silicon-macs\/\">How External Bootable Disks Work With Apple Silicon Macs<\/a><\/li>\n<li><a href=\"https:\/\/mjtsai.com\/blog\/2025\/03\/25\/error-702-installing-macos-on-an-external-drive\/\">Error 702 Installing macOS on an External Drive<\/a><\/li>\n<\/ul>\n\n<p id=\"failing-to-finish-updating-macos-on-an-external-disk-update-2025-05-13\">Update (<a href=\"#failing-to-finish-updating-macos-on-an-external-disk-update-2025-05-13\">2025-05-13<\/a>): Update (2025-05-13): With the final release of macOS 15.5, the problem got worse, and the Startup Disk workaround no longer helps.<\/p>\n\n<p>Previously:<\/p>\n<ul>\n<li><a href=\"https:\/\/mjtsai.com\/blog\/2025\/05\/13\/macos-15-5\/\">macOS 15.5<\/a><\/li>\n<\/ul>\n\n<p id=\"failing-to-finish-updating-macos-on-an-external-disk-update-2025-05-14\">Update (<a href=\"#failing-to-finish-updating-macos-on-an-external-disk-update-2025-05-14\">2025-05-14<\/a>): Erasing the external drive and doing a fresh install didn&rsquo;t help, either. The problem ended up being that I had plugged the external drive into the wrong USB-C port (the <a href=\"https:\/\/support.apple.com\/en-us\/120694\">DFU port<\/a>). I was aware of this requirement but had misremembered which port was which, forgetting that &ldquo;good&rdquo; port on my M4 and T2 Macs is in the same place as the &ldquo;bad&rdquo; port on my M1 Mac. I don&rsquo;t know why macOS can&rsquo;t just report an error when you use the wrong port instead of proceeding to install for an hour and then not report an error but not work, either.<\/p>\n\n<p id=\"failing-to-finish-updating-macos-on-an-external-disk-update-2025-06-26\">Update (<a href=\"#failing-to-finish-updating-macos-on-an-external-disk-update-2025-06-26\">2025-06-26<\/a>): <a href=\"https:\/\/mastodon.social\/@felix_schwarz\/114745377303602058\">Felix Schwarz<\/a>:<\/p>\n<blockquote cite=\"https:\/\/mastodon.social\/@felix_schwarz\/114745377303602058\"><p>Just spent hours trying to install macOS 26b2 on an external SSD. After rebooting, it just wouldn&rsquo;t complete but boot back into macOS on the internal SSD eventually.<\/p><p>Why? I had plugged the SSD into the wrong USB-C port[&#8230;]<\/p><\/blockquote>","protected":false},"excerpt":{"rendered":"<p>Juli Clover: Apple today seeded the fourth beta of an upcoming macOS Sequoia 15.5 update to developers for testing purposes, with the software coming a week after Apple released the third macOS Sequoia 15.5 beta. My update\/installer\/storage issues continue. I tried updating my external drive several times, but each time when Software Update restarted the [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"apple_news_api_created_at":"2025-04-29T17:58:26Z","apple_news_api_id":"9196fb26-c914-4d3f-9c5f-0f782639e0b4","apple_news_api_modified_at":"2025-06-26T18:54:22Z","apple_news_api_revision":"AAAAAAAAAAAAAAAAAAAAAw==","apple_news_api_share_url":"https:\/\/apple.news\/AkZb7JskUTT-cXw94JjngtA","apple_news_coverimage":0,"apple_news_coverimage_caption":"","apple_news_is_hidden":false,"apple_news_is_paid":false,"apple_news_is_preview":false,"apple_news_is_sponsored":false,"apple_news_maturity_rating":"","apple_news_metadata":"\"\"","apple_news_pullquote":"","apple_news_pullquote_position":"","apple_news_slug":"","apple_news_sections":"\"\"","apple_news_suppress_video_url":false,"apple_news_use_image_component":false,"footnotes":""},"categories":[2],"tags":[2806,30,2598,2087,2752,174],"class_list":["post-47549","post","type-post","status-publish","format-standard","hentry","category-technology","tag-dfu-mode","tag-mac","tag-macos-15-sequoia","tag-software-update","tag-startup-disk","tag-storage"],"apple_news_notices":[],"_links":{"self":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/47549","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/comments?post=47549"}],"version-history":[{"count":5,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/47549\/revisions"}],"predecessor-version":[{"id":48243,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/posts\/47549\/revisions\/48243"}],"wp:attachment":[{"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/media?parent=47549"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/categories?post=47549"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/mjtsai.com\/blog\/wp-json\/wp\/v2\/tags?post=47549"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}