Hi Sergei,
I can only imagine that it is something to do with the web configuration, so either something in the configuration file, access (for the users set up for running the respective services) or a setting in IIS (e.g. if running on a local host, have you stopped the "Default Web Site"?).
The web config file can be found in C:\Program Files (x86)\Blue Prism\Decipher Web\Web.config. Worth double checking this against the instructions.
Log files can be found in C:\Windows\SysWOW64\config\systemprofile\AppData\Local\Blue Prism and C:\Windows\System32\config\systemprofile\AppData\Local\Decipher.
Though the default logging level may not included sufficient information to resolve the error.
After checking the notes above, I'd recommend raising a support ticket so they global support team can guide you through updating the respective steps (which may include how to increase the respective logging levels).
Regards
Ben
Ben Lyons
Principal Product Specialist - Decipher
SS&C Blue Prism
UK based