Using JMeter today occurs when the flash back, DOS error figure, anyway JMeter flashed appeared this An error occurred: TOOLS. Online search has not found out what this is wrong child, I still look at the log bar.
E in JMeter installation directory: \ apache-jmeter-5.1 \ bin, see jmeter.log. Look there is a file not found error, the fact is ApacheJMeter_core-4.0.jar I personally put / lib / ext below.
And then found in the / lib / ext directory, also placed a ApacheJMeter_core.jar. I put between former ApacheJMeter_core-4.0.jar Jmeter is OK, and I suspect the conflict, after the decisive delete ApacheJMeter_core-4.0.jar, really good.
