{"id":270,"date":"2005-10-11T22:26:00","date_gmt":"2005-10-12T05:26:00","guid":{"rendered":"https:\/\/kb.terabyteunlimited.com\/kb-articles\/message-missing-operating-system-during-boot\/"},"modified":"2021-09-07T15:06:41","modified_gmt":"2021-09-07T22:06:41","slug":"message-missing-operating-system-during-boot","status":"publish","type":"lsvr_kba","link":"https:\/\/www.terabyteunlimited.com\/kb\/kb-articles\/message-missing-operating-system-during-boot\/","title":{"rendered":"Message &#8220;Missing Operating System&#8221; During Boot"},"content":{"rendered":"<strong>Problem:<\/strong><br \/>\r\n  <blockquote>When attempting to boot, you receive the following error message:<br \/><br \/><font color=\"#ff0000\">Missing Operating System<\/font><br \/><\/blockquote><strong>Cause:<\/strong><br \/>\r\n  <blockquote>This error message is generated by the MBR code and the problem can have a number of causes.&nbsp; The most common of these are as follows:<br \/>\r\n    <ul>\r\n      <li>The geometry (CHS) setting on the system has changed.<br \/><br \/><\/li>\r\n      <li>No partition is marked active.<br \/><br \/><\/li>\r\n      <li>An unbootable or unformatted partition is set active.<br \/><br \/><\/li>\r\n      <li>The hard drive is failing.<br \/><\/li>\r\n    <\/ul>\r\n  <\/blockquote><strong>Solution:<\/strong><br \/>\r\n  <blockquote>Ensure that the following conditions are met:<br \/>\r\n    <ul>\r\n      <li>If the problem is the result of geometry misconfiguration, correct it by setting the <strong>Mode<\/strong> (sometimes referred to as the <strong>Access Mode<\/strong>) in the system BIOS to <strong>Auto<\/strong> or <strong>LBA<\/strong>.&nbsp; In some rare cases, it is necessary to select <strong>Normal<\/strong> for this setting.<br \/><br \/><\/li>\r\n      <li>Mark the desired partition active.<br \/><br \/><\/li>\r\n      <li>Run the hard drive manufacturer's disk diagnostics on the drive. Use the most thorough test available.&nbsp; Below are links to some major hard drive manufacturer home pages: \r\n        <p><a href=\"http:\/\/www.hgst.com\/\" target=\"_blank\" rel=\"noopener\">HGST\/WD<\/a><br \/><a href=\"http:\/\/www.seagate.com\/\" target=\"_blank\" rel=\"noopener\">Seagate<\/a><br \/><a href=\"http:\/\/www.toshiba.com\/tai\/\" target=\"_blank\" rel=\"noopener\">Toshiba<\/a><br \/><a href=\"http:\/\/www.wdc.com\/\" target=\"_blank\" rel=\"noopener\">Western Digital<\/a><\/p>\r\n      <\/li>\r\n    <\/ul>\r\n  <\/blockquote>","protected":false},"excerpt":{"rendered":"<p>Problem: When attempting to boot, you receive the following error message:Missing Operating SystemCause: This error message is generated by the MBR code and the problem can have a number of causes.&nbsp; The most common of these are as follows: The geometry (CHS) setting on the system has changed. No partition is marked active. An unbootable [&hellip;]<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"lsvr_kba_cat":[1808],"lsvr_kba_tag":[2131],"class_list":["post-270","lsvr_kba","type-lsvr_kba","status-publish","hentry","lsvr_kba_cat-hardware-or-bios","lsvr_kba_tag-bios"],"_links":{"self":[{"href":"https:\/\/www.terabyteunlimited.com\/kb\/wp-json\/wp\/v2\/lsvr_kba\/270","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.terabyteunlimited.com\/kb\/wp-json\/wp\/v2\/lsvr_kba"}],"about":[{"href":"https:\/\/www.terabyteunlimited.com\/kb\/wp-json\/wp\/v2\/types\/lsvr_kba"}],"author":[{"embeddable":true,"href":"https:\/\/www.terabyteunlimited.com\/kb\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/www.terabyteunlimited.com\/kb\/wp-json\/wp\/v2\/comments?post=270"}],"version-history":[{"count":1,"href":"https:\/\/www.terabyteunlimited.com\/kb\/wp-json\/wp\/v2\/lsvr_kba\/270\/revisions"}],"predecessor-version":[{"id":6420,"href":"https:\/\/www.terabyteunlimited.com\/kb\/wp-json\/wp\/v2\/lsvr_kba\/270\/revisions\/6420"}],"wp:attachment":[{"href":"https:\/\/www.terabyteunlimited.com\/kb\/wp-json\/wp\/v2\/media?parent=270"}],"wp:term":[{"taxonomy":"lsvr_kba_cat","embeddable":true,"href":"https:\/\/www.terabyteunlimited.com\/kb\/wp-json\/wp\/v2\/lsvr_kba_cat?post=270"},{"taxonomy":"lsvr_kba_tag","embeddable":true,"href":"https:\/\/www.terabyteunlimited.com\/kb\/wp-json\/wp\/v2\/lsvr_kba_tag?post=270"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}