The delay is because the Department of Justice wishes to review the sale that also includes the disposal of a large tranche of patents.
The sale to Attachmate was announced in November last year and was due to be finalised by the end of March. The new owners are taking the company private.
While the sale has been approved by shareholders it is conditional on Novell finalising the sale of 882 patents to CPTN Holdings, a consortium led by Microsoft and including Apple, EMC and Oracle, for $US450 million.
Novell's 8K filing with the SEC says: "On March 4, 2011, each of the Company and CPTN certified as to its substantial compliance with its second request.
"In addition, at the request of the DOJ, the Company and CPTN have agreed to provide the DOJ with additional time to review the patent sale and not to close the patent sale prior to April 12, 2011. The Company remains committed to working with the DOJ as it conducts its review of the patent sale.
"The patent sale remains subject to the satisfaction or waiver of other closing conditions as set forth in the Patent Purchase Agreement, including, without limitation, the receipt of antitrust approval in Germany."
Objections to the sale were raised with the German authorities by the Open Source Initiative.
Novell reported a net loss in its first quarter after the announcement of the proposed sale.