Please try to give more precise information generally, which might give others a better understanding of issues you are facing.
Examples:
What was the actual error given?
The actual error is more informative than your description of the error. Posting the command and full output of sudo pacman -Syu in this case is much more useful.
Exactly what did that forum post tell you to do? At bearest minimum, a link to that might have been helpful; recreating the commands used in this thread is better.
Again, the outputs of these commands are more useful than (paraphrasing) “it didn’t work”.
Please observe information given below, and provide system information as described. This information may be obtained after booting to a Manjaro Live environment on the latest Manjaro Installer ISO, if needed.
Please take some time to familiarise yourself with Forum requirements; in particular, the many ways to use the forum to your benefit:
The Update Announcements should be checked frequently for important update related information.
These announcements contain a Known Issues and Solutions section and should generally be checked before posting a request for support.
Output of the following command formatted according to forum requirements (see links above) may be useful for those wishing to help:
inxi --admin --verbosity=8 --filter --no-host --width
Be prepared to provide more information and outputs from other commands when asked.
Regards.