User Warning about Module location

Since updating to 7.50, I get the following message (x4) after running cron…
“User warning: The following module is missing from the file system: danland. In order to fix this, put the module back in its original location. For more information, see the documentation page. in _drupal_trigger_error_with_delayed_logging() (line 1128 of /home/jcrogers/public_html/includes/”
This is one of 4 identical error messages, each specifying a different theme. Stark (the only core theme error) is located in public_html/themes, along with bartik, engines, garland, and sevenk. Note I’m getting above error for ONLY Stark of the core themes. The other 3 errors are for contributed themes, located in public_html/sites/all/themes. Here I have corporateclean, danland, marinelli and professionaltheme and I’m getting errors for all, except corporateclean.
I realize much is already written here about this problem with 7.50, and I’d really like to find and resolve this problem, but so far I’ve found no solution.
Help and advice are greatly appreciated. Thanks…

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