This page describes how to fix a bug in the dll of !EnergyPlus 6.0.0, build23 that may occur when exchanging a large amount of data in each time step. The error message that !EnergyPlus writes to its {{{.err}}} file is {{{ ExternalInterface starts first data exchange. Error: No digits were found in getDoubleCheckError. Further characters after number: Sending EXIT_FAILURE = : 1 **FATAL:Error in ExternalInterface: Check EnergyPlus *.err file. }}} To fix the bug, proceed as follows: = Windows = 1. Install the BCVTB version 0.8.0 1. Copy the file {{{bcvtb/lib/util/bcvtb.dll}}}, where {{{bcvtb}}} is the top-level directory of the BCVTB installation, to the !EnergyPlus directory, such as {{{C:\Program Files\EnergyPlus-6-0-0}}}. This will replace the existing file with the same name. = Linux = 1. Install the BCVTB version 0.8.0 1. Copy the file {{{bcvtb/lib/util/libbcvtb.so}}}, where {{{bcvtb}}} is the top-level directory of the BCVTB installation, to the !EnergyPlus {{{lib}}} directory, such as {{{/usr/local/EnergyPlus-6-0-0}}}. This will replace the existing file with the same name. = Mac = 1. Install the BCVTB version 0.8.0 1. Copy [[http://simulationresearch.lbl.gov/bcvtb/releases/0.8.0/dll/mac/32/libbcvtb.dylib|this file]] to the !EnergyPlus {{{lib}}} directory, such as {{{/Applications/EnergyPlus-6-0-0/lib}}}. This will replace the existing file with the same name. (Do not use the file from {{{bcvtb/lib/util}}}, since this is a 64-bit version, but !EnergyPlus requires a 32-bit version.)