"the losses from 2011, 2012 and 2013 returns are greater than the available amount of losses". Do I just send the tax return with this error? I don't know how to fix it.

As I understand it, you are not reporting the correct amount of losses from those prior years.  If you are requesting a loss carry forward, you will need to match the numbers for each year from your notice of assessment. You can also contact CRA for specific losses in specific years.  You will need info from your notice of assessment to prove identity.

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