Workflows Timeout Error at Flexi Task because database was full

Dear Community,

I got an issue with workflow, today at noon when users are using the application, the database got full & users can't do anything after that until I purge the logs database & increase the size of drives. Based on the error below in workflows.

After which things were fine for new items until we found that there is an issue with existing workflow instances too, so where ever users submitted tasks with some outcome it doesn't get updated in the workflow.

Users received emails with "No response required" after they submitted their response, but the main item workflow still showing running that task which is completed in the Nintex task list. Also, there are still remaining actions that never ran. Luckily I have verbose logging on for some testing which shows me an error under vTextError - 

Task History shows Pending task but, the workflow message shows Task Completed & Outcome is there a screenshot attached. Manager Task which is in yellow highlighted.

Any ideas on how to complete this remaining process or just terminate it? I can't restart the workflow as it's with multiple approvals. Right now users can see tasks under my workflow web part too. Also, there are remaining actions that I want to run on those faulty workflow instances.

Thanks in advance.

Sumeet