When running a BTXML in BarTender Designer, you receive Error Message 3908: Required white space missing.
Error 3908 covers a multitude of BTXML errors, so this article specifically covers this case.
BarTender 2016 and later
Take a look at the BTXML itself. Here is an example of the BTXML that caused this error. Note how the parameters use double quotes:
<XMLScript Version=""2.0"" Trusted=""true"">
For comparison, this is a properly formed BTXML script using single quotes:
<XMLScript Version="2.0" Trusted="true">
The error message refers to the double quotes. XML uses single quotes, so in this instance, BarTender assumes that the parameter value is contained between the quotes and a space, or a > should follow afterward.
To fix this issue, change all double quotes to single quotes and the error message goes away.