Factorio suddenly doesn't like spaces, neither in game path, nor in save names.
How I got this, is really confusing, so I am posting this in whole:
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I have these folders:
![Image](https://i.imgur.com/6ZbAbod.png?1)
Notice, that there is both Factorio and Factorio 0.17 folders - the former is 0.16.51 install, 0.17 is separate one for testing.
This is what I thought was the issue at first!
Next, I add some random mod, let the game restart, and sync a save with the mods...
![Image](https://forums.factorio.com/images/ext/cdaae26a8b24983f03a1e8d4ecaba887.png)
After restart I am greeted with following message:
![Image](https://forums.factorio.com/images/ext/fda5c7dda3880222b0b1d63853f86ce4.png)
Notice the path!
Then I land in the main menu.
After few tries I usually end up in the game, and everything looks to be working, though.
Then I rename the folders with other installations:
![Image](https://forums.factorio.com/images/ext/611ee81d758eaffcaa34112eb7236ac5.png)
Try to sync save with this mod again, and...:
![Image](https://forums.factorio.com/images/ext/9b14ce71a7f9a821658541d89c3edfb1.png)
removing and readding the mod still gives me the last message.
Finally I change the folder name to include underscore instead of space:
![Image](https://forums.factorio.com/images/ext/6d7dd3a3b320771ed4da3586088d7145.png)
And while synchronizing I get this:
![Image](https://forums.factorio.com/images/ext/7dc86a119c0e58cbd44aff8483d83ac8.png)
But wait, the name of the save... yes, it has a space!
So I quickly loaded the save (without sync), and resaved it:
![Image](https://forums.factorio.com/images/ext/ad52ad001cd5d79ff930c0c45b59e0b8.png)
And presto:
![Image](https://forums.factorio.com/images/ext/b0f8470035cc74822ba61aacb9839484.png)
Conclusion: don't use spaces.