Illustrator CC 2018 - Stroke Thickness Bug

What OS version are you? Does not happen for me on Mac Sierra.

This appears to be a plug in or system software that is conflicting. Avast anti virus software did something similar, but we stopped seeing reports for that several months ago. Do you have anything installed that affects you system, from wacom to an illustrator plug in.

Thanks for reporting.

We are able to reproduce the issue at our end and will look into this.

However the issue get reproduce when we are using comma(,) as a separator.When I am using dot(.) as a separator I was not facing this issue.

Regards,

Mohd Ziaullah

Illustrator Team

When you installed CC 2018 if you did not have “Import previous settings and preferences” unchecked in the Advanced Options then that may be the cause of your problems (see screen shot). A number of issues which have seemed like they could be bugs have been fixed with the process described below:

If you had “Import previous settings and preferences” checked during the install then you will have to manually make sure that all previous preference files for Illustrator are deleted (or if on a PC renamed) making sure that Illustrator is closed when you do so. You can then open CC 2018, save a test file and then quit it so that a new CC 2018 only preference folder will be created. (This is all based on a test I did that showed that when an older preference file exists CC 2018 did not create a complete preference folder). At this point I would restart the computer and once rebooted launch Illustrator and hopefully your problem will be solved.

To manually delete preferences:

For Macintosh Users: With Illustrator closed launch a Finder Window in column view and click on your home folder. With the Option Key pressed choose Library from the Finder Go Menu. Within the Library folder find the folder called Preferences and within it find the following two files and delete them: “Adobe Illustrator <Version #> Settings” (earlier versions of Illustrator might just say “Adobe Illustrator”) and “com.adobe.Illustrator.plist”. When Illustrator is next launched it will create new preference files and the program will be restored to its defaults.

For Windows Users:

For Windows Users: You can try the quick way of resetting on a PC which is to hold down Ctrl + Alt + Shift when launching Illustrator and respond affirmatively when asked if you want to reset. There have been some recent reports that the window asking if you want to reset is not popping up but that the prefs are being reset anyway. If this works then great but if it doesn’t you may have to manually delete them.

On Windows 7 and above the preference files are hidden. To find them go to the Control Panel and open Folder Options and then click the View tab. Then select “Show hidden files and folders” or “Show hidden files, folders or drive options” in Advanced Settings (you may be able to skip the previous steps with Windows 10). Then delete (or rename) the folder at the end of this path: C:\Users\[User Name]\AppData\Roaming\Adobe\Adobe Illustrator [version number]\ Settings\<Language> for any versions that you have. Make sure that Illustrator is closed when you do this. When you relaunch the program it will create  new preference files and the program will be at its default settings.

After you’ve reset up the program (make sure that no document window is open) to your liking, it is a really good idea to create copies of your personalized “mint” preference files (make sure that you quit the program before copying them—that finalizes your customization) and use them in the future to replace any corrupt versions you may need to delete.

Hopefully this process will fix the problems that you have presented.