First, we'd like to know your answer toFiat Lux - ASIA clarifying questions. This helps us address your concern and provide further information related to it.
Based on the error you've got, you have a large number of lists to import in QuickBooks Online. That's why the system prompts an error similar to yours.
We can utilize the Condense Data within your company file, it allows you to reduce the size of your file. Note: Condensing data in your account is irreversible.
Select File, then Utilities, and then Condense Data.
As illustrated below, choose the first choice. Please note that the system will inform you of the approximate file reduction.
Click Next, the message Working on your file now will show. When the optimization is finished, a window appears, informing you of the total file size reduction as well as the location of the backup file created before the optimization.
Also, you can check about moving data from QuickBooks Desktop (QBDT) to QuickBooks Online (QBO):