The issue can occur if gacutil left the empty folder in the \GAC_MSIL\ after uninstalling the previous version of a dotConnect provider. This is a very rare case in fact.
The Global Assembly Cache can be found here:
But you can't simply open the folder by standard Explorer.
Use a file manager (for example, Unreal Commander) that allows you to see hidden and system files and run it with system administrator permissions. Then delete the Devart.Data folder.
If you don't have any file manager other than Explorer, then you can use Explorer with the GAC shell extension turned off. The GAC shell extension connects to Explorer using the Desktop.ini file located in the assembly folder. Rename the Desktop.ini file to display the content of the assembly folder like content of any other folder. For this, run the following three commands in Command Prompt:
1. Go to the GAC folder:
2. Remove the system and hidden attributes for the Desktop.ini file:
attrib –s –h desktop.ini
3. Rename the file to disable the shell extension
ren Desktop.ini Desktop.ini.disabled
After this, use Explorer to go to the %windir%\assembly\GAC_MSIL\ folder and delete the Devart.Data folder.
Finally, rename the Desktop.ini.disabled file back to Desktop.ini.