Assuming that you are referencing importing contacts(Was pretty sure you were, but wanted verification), we recently fixed a bug that was accidentally allowing unlimited size imports which had the potential to cause reliability issues. The limits for imports are listed in this kb article. We are allowing double the documented limit for API imports. You will need to split your import into multiple calls.
Surely there is a workaround? I will have to split into several calls. And I’m sure there are larger companies that have many millions of customers… what are they doing?
@Ron_at_BRCC we’ve faced similar issues with these errors. Our best workaround is an automated process to generate multiple smaller files that the HubSpot API will accept. We check each file for the row size, and split the file into multiple smaller files if it’s under the limit.