When viewing graph data, non-numeric values may appear

[jaevan21]

Cacti Version | 1.2.19
Cacti OS | unix
NET-SNMP Version | NET-SNMP version: 5.8
RRDtool Version Configured | 1.7.2+
RRDtool Version Found | 1.7.2
Poller Type | SPINE 1.2.19

To recreate the issue: go to any graph and click on utility view. A popup window appear with 500 internal server error.
cacti.log output

2021-11-09 06:52:32 - ERROR PHP ERROR: Uncaught TypeError: round(): Argument #1 ($num) must be of type int|float, string given in /usr/share/cacti/graph_xport.php:266 Stack trace: #0 /usr/share/cacti/graph_xport.php(266): round() #1 {main} thrown in file: /usr/share/cacti/graph_xport.php on line: 266
2021-11-09 06:52:32 - CMDPHP PHP ERROR Backtrace:  (CactiShutdownHandler())

[netniV]

Try the above patch, that should at least allow things to be viewable without crashing the code. From there, you may find another issue.