When Blazemeter performance tests run into errors (as listed in the errors tab), it often proves to be useful to examine the error.jtl file.
This file is included in artifacts.zip, downloadable from the logs tab. The file holds full details of all failed samplers but is hard to read by any editor.
To improve readability, it is recommended to load the file into Jmeter's View Result Tree Listener
However doing so, it may become apparent that the number of entries in this listener is far less than the number of errors reported in the Blazemeter errors tab.
Because of this, a particular error that you are trying to resolve may not be included in the View Result Tree Listener, making it impossible to determine the root cause of that specific error.
The View Result Tree listener, by default, only loads and lists 500 entries of each file uploaded to it, eversince JMeter 3.2
The jmeter.properties file of your local JMeter (located in its /bin directory) has following content:
# Maximum number of results in the results tree
# Set to 0 to store all results (might consume a lot of memory)
To load more entries, uncomment that last line (remove the #) and set it to the desired value, then restart JMeter and load the error.jtl once again.
Be aware that this might consume a lot of memory.