Maintenance of the bank or financial institution’s website might result in QuickBooks banking error 102 in QuickBooks online.
Other causes for QuickBooks banking error 102 to occur:
Technical issues.
Difficulty in sending data.

To fix QuickBooks banking error 102:
You must check your login info at the financial institution’s website.
If the error arises due to maintenance at the bank's end, then wait for the bank to resolve it.
Gets quick support in fixing QuickBooks banking error 102, call QuickBooks enterprise support at +1-888-485-0289 or visit here: https://www.quickbooksenterprisesupport.com/quickbooks-banking-error-code-102-easy-steps/