Error computing Explicit (SWMM) solver: "Error 211: Invalid number"

  Product(s): Bentley SewerGEMS, Bentley CivilStorm
  Version(s): CONNECT Edition, V8i
  Area: Other


When computing a model using the Explicit (SWMM) solver, it fails, generates a red user notification stating "The SWMM engine failed during the calculation..." and in the SWMM Calculation Summary, the following error is seen:

"Error 211: Invalid number"


This issue can occur in a number of different situations where there is an issue with the data entry for elements.

First, make sure that you have the latest version of SewerGEMS or CivilStorm installed, as well as the latest patch set. You can use the instructions at this link to find the latest installation file.

If that doesn't help with the issue, check the data input for the element label referenced in the error message.

  • If the element is a pump, make sure the pump data and on/off elevations are accurately entered.
  • If the element is a tank/wetwell, make sure that the elevation range makes sense (i.e., the maximum elevation is higher that the minimum). If you are using Level for the elevation type, make sure the the data is correct relative to the base elevation of the tank.
  • If the element is a conduit, ensure that any control structure or culvert settings are current. For version and earlier, there is a known issue (reference # 686176) causing the error in question to show for a conduit with label suffice "_OW", referring to a conduit that is not set as a culvert, but had been set to one in the past, with the Overtopping Weir setting set to true. If this occurs, choose "true" for "Is culvert", change the "Has overtopping weir?" setting to false, then switch the Is Culvert setting back to False and try again.