I have this error too

Application server composants:
Apache 2
MySql 5.1.30
PHP Version 5.2.8
jpgraph 2.1.x and last 2.3.4

Mantis 1.2.0a3 2009-02-14-master-37de009

I have error:
Image "url" cannot be showed, because has error. (This my free translation from russia)

I also have the same problem, I've tried on two different configurations.

Windows XP with Apache 2.2, PHP 5.2.6, JPGraph 2.3.4, MySQL 4.1.22
CentOS 5.2 with Apache 2.2.3, PHP 5.1.6, JPGraph 2.3.4, MySQL 5.0.45

I have two version of Mantis. One was unpacked from the 1.2.0a3 archive, this works. The other is a development version I am using for some workflow changes, downloaded from GIT just a day or two ago. The one from GIT is broken, with none of the graphs operational.

I get the same error when displayed with FireFox (Image "url" cannot be displayed because it has errors).

I've investigated summary_graph_bystatus.php, and can confirm that the data for the graph is being collected correctly via create_bug_enum_summary. I have tried replacing core.php, graph_api.php and the status summary graph files with those from the operational installation I have, but that makes no difference, the graphs are still broken.

Tnx Paul.
Solvation:
check your mantis folder for BOM-signature in all files. Remove this and check. For me it's helps.

I've scanned all the files for all 5 different Unicode BOMs and have only found three files with a BOM, none of which are of any consequence (I deleted them all). It's made no difference to the problem. But thanks for the suggestion.

Maybe the problems are the same as described at 0012410

lmaille, this issue is not reproducible with current version of MantisBT and the provided information.
Feel free to reopen the issue if there are still problems after upgrading.