The source advises (citation):

Notice
As of January 2019, the Bank of Canada will no longer publish the daily, weekly, or monthly prime commercial paper (CP) or bankers' acceptance (BA) rates.

In response, we have marked the series as "discontinued" in their metadata and segregated in the catalog. There is no direct replacement at this time.

Dataset properties:

• Measurement: Percent per annum (%)
• Adjustment: Not seasonally adjusted (NSA)
• Native frequency: Business-daily
• Date range: 14 November 2002 to 31 December 2018

The series reside in the historical catalog (Canada » Financial » Interest rates » Money market rates) and are

• IR%NEW1UD.ICAN = [DISCONTINUED] Interest Rates: Prime Corporate Paper - 1-Month, (%, NSA)
• IR%NEW2UD.ICAN = [DISCONTINUED] 2-month
• IR%NEW3UD.ICAN = [DISCONTINUED] 3-month

Because catalog locations are subject to change, the upper-right search box on DataBuffet.com provides a "find in catalog" mode that accepts a mnemonic.