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Topic: Apache 2.4.66 VS18 httpd crashes PHP 8.5.1

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Topic: Apache 2.4.66 VS18 httpd crashes PHP 8.5.1

[axel.kam]

[admin]

I asked AI :

Status 3221226356 (0xC0000374) = heap corruption → mostly :

❗ PHP DLL mismatch
❗ Verkeerde VC++ runtime
❗ Foute / corrupte PHP extension
❗ TS vs NTS fout (they advise TS)

[admin]

Extra info :

❗ Windows heap corruption
❗ Memory overwrite
❗ Double free
❗ Thread race condition

Dat wijst bijna altijd op:
• PHP extension bug
• mod_php + threads conflict
• OPCache memory issue
• DLL mismatch
• 3rd party module

[axel.kam]

[nono303]

Hi @axel.kam,

[Crafted]

[tangent]

Reviewing this lengthy thread over Apache stability, I'm concerned it appears to be focusing on HTTPD build code, rather than considering a resource issue that could well be resolved with configuration changes.

In particular, I note no one's mentioned ThreadStackSize or ThreadsPerChild.

Historically, I came across any number of Windows setups where the default thread stack size wasn't enough, and seem to recall MS chose a lowly figure of 1MB. I'd want to match a Linux figure of 8MB, and scale ThreadsPerChild according to system resources and the available memory. That in turn depends on what else is running on the server, PHP, database, etc.

With mpm_winnt, there is only one process, so you need to allocate sufficient threads to support the expected connection load. In one part of the post, I note Axel.Kam's log mentions 192 worker threads, which sounds pretty low to me. Even if you set ThreadsPerChild at 512, with ThreadStackSize at 8MB that would only take up 4GB of thread stack memory if all threads were active.

The other parameter I used to change was MaxConnectionsPerChild which defaults to 0, meaning unlimited. If any module linked to a child process leaks memory, then eventually it will fail and crash. Limiting the number of connection requests it serves can circumvent this problem, at the expense of some extra overhead in restarting that child process.

If it's not impertinent, resource permitting, I'd suggest considering trying something like this:

[Crafted]

[RikasMalinka]

I’ve been running Apache HTTP Server 2.4.66 Win64 (build 260223) for more than 24 hours now, and there have been no crashes so far.

This is the most stable run I’ve had with version 2.4.66 to date.

[tangent]

@RikasMalinka - thanks for the positive update.

@Crafted - apologies, you had mentioned ThreadStackSize before, though I still stand by the MaxConnectionsPerChild issue.

If I read the thread correctly, you've reported the same heap error exit code 3221226356 (0xc0000374) with differing version of OpenSSL (3.5 LTS as well as 3.6 series), differing versions of Visual Studio, and differing versions of PHP. But only it would seem Apache/2.4.66.

As noted, Steffen has updated the Apache/2.4.66 download viz: https://www.apachelounge.com/viewtopic.php?p=44104#44104 to "Apache 2.4.66-260223 Win64".

This is a notable change which now matches the previous VS builds, in that they too didn't have defined base addresses per module. It turns out by default the HTTPD CMake configuration file assigns a base address to each module, rather than leaving it to the OS loader (and ASLR). This may affect stability.

I'll be updating the CMake build HowTo soon, to reflect this change.

If you're able, could you please try this latest build of Apache/2.4.66?

[axel.kam]

[mrdj1024]

my setup
cpu : amd fx 6300
os : win11
ram : 16 gb
using php 8.4.18(by jan-e of these forums) in fcgid mode
no issues seen in this newer apache version.

[nono303]

[admin]

@nono303 Next release I try to make it available.

[axel.kam]

A bad result is already a result.
If I'm reading the results correctly, Application Verifier showed that the mod_http2 causing the error. This is unexpected.

PC has 64 GB of RAM, and at startup 20 GB is immediately allocated to system, service, and the RAM disk.

[Thu Feb 26 02:40:56.320751 2026] [mpm_winnt:notice] [pid 8816:tid 312] AH00428: Parent: child process 15068 exited with status 3221226529 -- Restarting.
[Thu Feb 26 02:40:57.558492 2026] [mpm_winnt:notice] [pid 8816:tid 312] AH00455: Apache/2.4.66 (Win64) OpenSSL/3.6.1 configured -- resuming normal operations
[Thu Feb 26 02:40:57.558492 2026] [mpm_winnt:notice] [pid 8816:tid 312] AH00456: Apache Lounge VS18 server built: Feb 23 2026 10:01:09


First chance access violation for current stack trace. 20659da60b8 - Invalid address causing the exception. 7ff8c348cabb - Code address executing the invalid access. 35871ff2b0 - Exception record. 35871fedc0 - Context record. vrfcore!VerifierUnregisterLayer+57d ( @ 0) verifier!VerifierStopMessage+bc ( @ 0) ntdll!RtlApplicationVerifierStop+95 ( @ 0) vfbasics!+7ff86b8d2a1f ( @ 0) vfbasics!+7ff86b8d3cd4 ( @ 0) vfbasics!+7ff86b8d48aa ( @ 0) ntdll!RtlLocateExtendedFeature+f96 ( @ 0) ntdll!RtlLocateExtendedFeature+366 ( @ 0) ntdll!KiUserExceptionDispatcher+2e ( @ 0) mod_http2!+7ff8c348cabb ( @ 0) mod_http2!+7ff8c348da54 ( @ 0) mod_http2!+7ff8c3493219 ( @ 0) mod_http2!+7ff8c34847c9 ( @ 0) mod_http2!+7ff8c34846a5 ( @ 0) libhttpd!ap_run_process_connection+3d ( @ 0) libhttpd!ap_process_connection+31 ( @ 0) libhttpd!ap_run_generate_log_id+3e4e ( @ 0) vfbasics!+7ff86b8e7943 ( @ 0) KERNEL32!BaseThreadInitThunk+17 ( @ 0) ntdll!RtlUserThreadStart+2c ( @ 0)

"we need to think about it"

PS. The big files are distibuted via https and VS17 work fine with this task

[axel.kam]

[axel.kam]