Issue ''no free slots on server'' - please help!!

[Chimba]

Guys, I have a bug here in my game and I wanted to know if anyone knows how to solve it, I was playing with my girlfriend for a while, and today when we started playing she is not able to connect to our farm, she keeps saying "there is no enough space on the server" when there is no one but me on the server. Can anyone help me? She already had her character and it started to appear out of nowhere, even with her cabin there already built and with no one but me on the server this appears and she can't connect.
We don't want to lose our farm that we've played for so long, if I delete her cabin her character disappears and we didn't want that either.

 

[MysticTempest]

Howdy, I'm not familiar with this error other than through the common issue of no cabins.
But, it's interesting.

Has she by any chance changed her Steam name, or is joining from a new location; or something along those lines?
Something may have changed her userid so that she's not recognized as the owner of the character.

---
I know with regards to multiplayer data, you could try deleting the "UserID" data from her farmhand's section. Which may allow her to takeover the character again.

Find your saves, then make a backup:

Saves - Stardew Valley Wiki

The game saves progress when the in-game day ends, i.e., when the farmer goes to bed, collapses from exhaustion, or collapses at 2am. All progress during a day is lost if the player quits the game without ending the day. In multiplayer, the game saves after all players click through the prompts...

stardewvalleywiki.com

Then you can edit the save:

Saves - Stardew Valley Wiki

The game saves progress when the in-game day ends, i.e., when the farmer goes to bed, collapses from exhaustion, or collapses at 2am. All progress during a day is lost if the player quits the game without ending the day. In multiplayer, the game saves after all players click through the prompts...

stardewvalleywiki.com

Then you'll want to search for the following: <userID>
If you start from the top, the first will be yours, and the 2nd one should be hers.

It'll have a random number in it like so:
Example userid

<userID>196488016406982121</userID>

Delete that line, and replace it with this:

<userID />

That clears out the ID code of the player.

Proceed with saving your changes. And, retry letting her join.

 

[Chimba]

Howdy, I'm not familiar with this error other than through the common issue of no cabins.
But, it's interesting.

Has she by any chance changed her Steam name, or is joining from a new location; or something along those lines?
Something may have changed her userid so that she's not recognized as the owner of the character.

---
I know with regards to multiplayer data, you could try deleting the "UserID" data from her farmhand's section. Which may allow her to takeover the character again.

Find your saves, then make a backup:

Saves - Stardew Valley Wiki

The game saves progress when the in-game day ends, i.e., when the farmer goes to bed, collapses from exhaustion, or collapses at 2am. All progress during a day is lost if the player quits the game without ending the day. In multiplayer, the game saves after all players click through the prompts...

stardewvalleywiki.com

Then you can edit the save:

Saves - Stardew Valley Wiki

The game saves progress when the in-game day ends, i.e., when the farmer goes to bed, collapses from exhaustion, or collapses at 2am. All progress during a day is lost if the player quits the game without ending the day. In multiplayer, the game saves after all players click through the prompts...

stardewvalleywiki.com

Then you'll want to search for the following: <userID>
If you start from the top, the first will be yours, and the 2nd one should be hers.

It'll have a random number in it like so:
Example userid

<userID>196488016406982121</userID>

Delete that line, and replace it with this:

<userID />

That clears out the ID code of the player.

Proceed with saving your changes. And, retry letting her join.

Yes, she recently moved house, however she didn't change her steam name.

I will try to carry out the procedures that you commented that could work, if it works I will come back here to let you know.

Thanks a lot for helping me!