Memorize and use the phrase, "I did my job to the best of my abilities, I had no idea that my performance was not adequate. I always tried to do the best I could, I had no idea my job was in jeopardy." If you had no warnings or indications that your performance was not up to snuff, be sure to throw that into the mix.
What is in your personnel file isn't important. What you say, versus what they say, is how the decision is going to be made. you tell your side of the story, which is that you had no feedback that showed your performance wasn't measuring up, you had no opportunity to change you behavior and keep your job.
"Not a good fit" is a very poor reason to terminate, and will probably be found to be non-fault on your part. If you weren't working out, but they didn't tell you, didn't let you know how you weren't working out, gave you no opportunity to change your behavior and keep your job, then it's a non-fault termination. The system has not sacred regard for personnel files. They work under the assumption that both you and the employer may not be telling the truth. they select the most believable of the two sides to this story.

