Before you use the procedure in this guide, you should probably:

• Check if the mission isn't active,
  
• Check if the mission isn't working in all your autosaves,
  
• Try to remember if there are any conditions you missed, e.g. "Meet us in the spaceport in an hour."

If nothing like that works, proceed.

As it has been posted in multiple places on the steam forums, here are the pathways to follow through your files:

Linux: ~/.local/share/endless-sky/saves/
Windows: C:\Users\<Your Username>\AppData\Roaming\endless-sky\saves\
Mac OS X: ~/Library/ApplicationSupport/endless-sky/saves/

*Note that these folders may be hidden:

To fix that, go to the View tab, and check the Hidden Items box.


The rest is pretty straight-forward from there.

The save file is a pretty long and somewhat confusing thing.
(Remember, MZ made it so we normies could understand it, but it's still code, in a way).

To get to the missions, press Ctrl (Command for Mac) + F, and search for "offered".

Scroll a little, and you are in the missions section.

Most missions should look like the highlighted pair:

They should have an offered and a done:

Look for the chain that you were locked out of, and find a mission that has a lonely "offered" that isn't paired with a "done".

Suppose my file looked like this:

What you would do then is delete the lonely "offered".

Now, my save file should look like this:



Now, just go to the place where the mission is offered normally, and it should be offered to you again.

All of this was taught to me by the community,
The shortcut is often referenced by Kiko.

If you want to know more about save files, here's a link to Derpy's guide on them.

Hope this was helpful, and tell me if I missed anything!
(Or if you have an idea for a better guide icon, lol).