Error: Decompression functionon

I suspect that you haven't recorded the script with the necessary headers. Go to the recording options>http properties>headers.

Ensure that your list of headers to record contains:
1. Accept encoding
2. Content encoding
3. Accept languages
4. Pragma
5. Transfer encoding
6. User agent
7. Accept- Charset
8. Accept
9. Cache control.

These are the most commonly used header tokens used in http 1.1.

Now, what happens if you don't record the accept encoding/content-encoding header is that if your server response/request is expected to be in compressed/deflated(which is defined in web server settings) form, but if Loadrunner/Client sends an uncompressed/inflated file/message, then the protocol goes out of sync. As a result, the Loadrunner compression function would expect the data to be in gzip format but the data sent from server would not be in gzip format and hence the error.

Add web_add_auto_header("Accept-Encoding", "gzip") on top of the request where your script stops and throws the error. But, I would suggest you to re-record the script with the aforemention headers in your recording list.

-Chaitanya M Bhatt
http://www.performancecompetence.com
2010/7/21 Anuj Sharma
Can any body guide me for this issue in load runner.

Error -26601: Decompression function (wgzMemDecompressBuffer) failed,
return code=-3 (Z_DATA_ERROR), inSize=1773, inUse=5, outUse=0,
Snapshot Info [MSH 0 13] [MsgId: MERR-26601]

This is application error or load-runner configuration issue?