You might want to check that the pyephem module is still available to WeeWX, this could be the problem if in upgrading WeeWX you moved from python 2 to python 3. If you are running WeeWX v4.7.0 or later check the WeeWX startup log to see if pyephem was found, you should see one of the following two entries in the log:
'pyephem' detected, extended almanac data is available
or
'pyephem' not detected, extended almanac data is not available
(While looking in the startup log take note of the python version being used by WeeWX, you will need it later if re-installing pyephem. It will be near the start of the startup log.)
If you saw the latter WeeWX did not find pyephem and you should first try re-installing pyephem as outlined below. If you are running WeeWX v4.6.2 or earlier you will not see either of the above messages, you will need to check for pyephem manually. Look in the log for the python version WeeWX is running under, you will see this logged by WeeWX during WeeWX startup. Note that depending on your system it may be different to the version used when executing the python command from the command line. If WeeWX is using python 3 what do you see when executing the following from the command line on your WeeWX machine:
$ python3 -c "import ephem; print(ephem._version__)"
If WeeWX is using python 2 try:
$ python2 -c "import ephem; print ephem._version__"
If you are presented with a version number similar to the following then pyephem is loaded:
$ python3 -c "import ephem;print(ephem.__version__)"
4.1.3
If you get a ModuleNotFoundError then pyephem is not installed and you will need to install it for the python version used by WeeWX.
To re-install pyephem under python 3:
$ sudo apt install python3-ephem
For python 2:
$ sudo apt-get install python-dev
$ sudo apt-get install python-pip
$ sudo pip install pyephem
Stop WeeWX if it is running and try running WeeWX directly, do you see MaxSolarRad in the output? If so exit and restart WeeWX as a daemon as per normal. If not let us know.
Gary