I know it may be not your responsibility but I remember there was the same case when the game had major update previously and was fixed with X-tools update.
Basically since 4.1 release I always get the Error Code 2 from Steam workshop when updating the VRO mod, while official doc says that it relates to steam servers down its definitely not the case (other people uploaded new mods in the meantime) and looking through the google it seems that this error can occur for many reasons, including size limit or X-tools issues.
So, can I please ask if its possible for someone to check the functionality of the X-tool? My mod update is 251 MB heavy, can be due to size limit set by Egosoft or something?
I tried solutions form the other sources mentioned below, but neither helped.
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1. Find your Steam install directory in windows explorer.
2. Right click, Properties.
3. Select the "Security" tab.
4. Check for the presence of "Users" in the "Group or user names" box.
5. If it's not present, they can select "Edit", find "Users" in the next window and select "Add"
Or:
1. Disable The Family Sharing Feature.
2. Verify Your Game Files.
3. Change The Download Server.
4. Reinstall Steam.
2. Right click, Properties.
3. Select the "Security" tab.
4. Check for the presence of "Users" in the "Group or user names" box.
5. If it's not present, they can select "Edit", find "Users" in the next window and select "Add"
Or:
1. Disable The Family Sharing Feature.
2. Verify Your Game Files.
3. Change The Download Server.
4. Reinstall Steam.