When I try posting the adjusting journal entries to the previous year, Adagio creates an error batch. When I view the batch it shows no errors. Allow posting to previous year is checked off.

Check the fiscal calendar and make sure period 12 is not closed. (This will also prevent posting to the YE adjustment period on Ledger 9.0.)

Is data integrity clean?

Are you saying that printing the batch listing reports no errors, but the batch cannot be posted? We are not aware of any behaviour such as this. What version of Adagio Ledger is in use?

What do have set for the company profile option 'post invalid entries to error batch'? If there are any valid entries in a batch, this optin controls whether they are posted (and bad entries go to the error batch), or nothing gets posted.

The posting journal report has a secondary error report - if you preview the posting journal, does this give you any information as to the errors?

If you edit the grid for the list of batches, you can add the 'Errors' column, to see how many errors have been determined are in the batch by the Batch Listing report. If this value is not zero, the batch will not post, and these errors will be listed on the report.