At install time, WMD checks to see if it can create the sites/default/webauth directory in webauth_requirements
It does so using a function called file_check_directory()
This function, in turns, calls file_directory_temp()
This one calls variable_set() to set the temp directory if it's not set yet (it's not)
variable_set tries to save the tmp directory value to the variable table and fails.
The problem is that the variable table doesn't exist yet when the site is being installed.
The fix is to use regular PHP functions to check and create the sites/default/webauth directory.
At install time, WMD checks to see if it can create the sites/default/webauth directory in webauth_requirements It does so using a function called file_check_directory() This function, in turns, calls file_directory_temp() This one calls variable_set() to set the temp directory if it's not set yet (it's not) variable_set tries to save the tmp directory value to the variable table and fails.
The problem is that the variable table doesn't exist yet when the site is being installed. The fix is to use regular PHP functions to check and create the sites/default/webauth directory.