That is 99% of the time a cache/cookie issue:

To resolve that error message, please try the following troubleshooting steps.

1.  Make sure that you’re using either Google Chrome or Firefox for QuickBooks Online.

2. Clear all of your browser’s cache and history, close the browser fully then log back into QBO again.

3.  […]

Resolution for 'browser fully issue: 'If while uploading CSV data the error message ‘something is not right’ appears – how do I find out what the error acutually is so I can corrrect it?' available: Yes.

The browser fully 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 browser fully issue yourself by looking for a resolution described in the article. If it is a complex browser fully issue or you are unable to solve the issue, you may contact us by clicking here or by using other browser fully support options.

For more information about resolving issues related to browser fully in Quickbooks/QBO or to get support for the issue 'If while uploading CSV data the error message ‘something is not right’ appears – how do I find out what the error acutually is so I can corrrect it?', click the link below: