QB Issue Resolution:

as long as you had the subscription, just enter the journal entry and back date it.  you can not make entries dated before you started the subscription

Resolution for Issue 'How do I post yearend adjusting journal entries in prior yearend.' available: Yes (Solved).
Source: Intuit Community forum.

How do I post yearend adjusting journal entries in prior yearend.: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

Support for back date
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Error Recovery for back date [Canada]
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