Hi @Lazar_Stosic,
The review_rounds_submission_id_stage_id_round_pkey message can be resolved per the instructions at Upgrade to 3.0.0: pkey violation on review_rounds · Issue #1921 · pkp/pkp-lib · GitHub – it’s a data error in your OJS 2.x install that’s causing trouble with the 2.x to 3.x upgrade process.
Regards,
Alec Smecher
Public Knowledge Project Team