Error 500 in backend after fresh install

[Ch3vr0n]

Just installed PS 9.0.1, PHP 8.4.14 is active. Frontend works but backend immediately gave error 500. After searching i found https://prestashop.com/blog/tech-en/what-is-the-http-500-error-and-how-can-i-fix-it-in-my-prestashop-online-store/.

Modifying line 36 from define('_PS_MODE_DEV_', false); to define('_PS_MODE_DEV_', true);

renders the backend operational. 

What's going wrong here and how do i get it fixed. Dev mode should not be enabled afaik, and certainly not after a fresh install. After succesful login (with dev mode enabled), if i then go into advanced settings and deactivate debug mode, the php value switches back to "false" but debug mode remains active in the black bar on top. Something's not right here. 

Error logs (scrubbed from private username and domain info) below

200 	<user> <user> 	Fout (3) 	SymfonyCacheClearer: Error while clearing cache for admin env dev using PrestaShop\PrestaShop\Adapter\Cache\Clearer\Symfony\ApplicationKernelCacheClearer: Warning: is_dir(): open_basedir restriction in effect. File(Doctrine\ORM\Mapping\ClassMetadata) is not within the allowed path(s): (/var/www/vhosts/<domain.tld>/:/tmp/) 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:24:38 	
198 	<user> <user> 	Fout (3) 	ExecKernelCacheClearer: Could not clear cache for admin env dev result: 127 output: array ( 0 => 'sh: php: command not found', ) 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:24:27 	
193 	<user> <user> 	Fout (3) 	ExecKernelCacheClearer: Could not clear cache for admin env prod result: 127 output: array ( 0 => 'sh: php: command not found', ) 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:24:15 	
188 	<user> <user> 	Fout (3) 	ExecKernelCacheClearer: Could not clear cache for admin env prod result: 127 output: array ( 0 => 'sh: php: command not found', ) 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:51 	
187 	<user> <user> 	Fout (3) 	SymfonyCacheClearer: Something went wrong while clearing cache: Warning: require(/var/www/vhosts/<domain.tld>/httpdocs/var/cache/prod/admin/ContainerMUl5lfa/getFilesystemKernelCacheClearerService.php): Failed to open stream: No such file or directory 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:49 	
186 	<user> <user> 	Fout (3) 	SymfonyCacheClearer: Error while clearing cache for admin env prod using PrestaShop\PrestaShop\Adapter\Cache\Clearer\Symfony\ApplicationKernelCacheClearer: Warning: require(/var/www/vhosts/<domain.tld>/httpdocs/var/cache/prod/admin/ContainerMUl5lfa/getHookModuleFilterService.php): Failed to open stream: No such file or directory 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:49 	
184 	<user> <user> 	Fout (3) 	ExecKernelCacheClearer: Could not clear cache for admin env prod result: 127 output: array ( 0 => 'sh: php: command not found', ) 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:37 	
179 	<user> <user> 	Fout (3) 	ExecKernelCacheClearer: Could not clear cache for admin env prod result: 127 output: array ( 0 => 'sh: php: command not found', ) 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:16 	
114 	<user> <user> 	Fout (3) 	Cannot register tab "PsshippingKeycloakAuthController" because it already exists 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:10 	
113 	<user> <user> 	Fout (3) 	Cannot register tab "PsshippingConfigurationController" because it already exists 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:10 	
112 	<user> <user> 	Fout (3) 	Cannot register tab "PsshippingConfigurationController" because it already exists 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:10 	
111 	<user> <user> 	Fout (3) 	Cannot register tab "PsshippingConfigurationController" because it already exists 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:10 	
110 	<user> <user> 	Fout (3) 	Cannot register tab "PsshippingConfigurationController" because it already exists 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:10 	
109 	<user> <user> 	Fout (3) 	Cannot register tab "PsshippingConfigurationController" because it already exists 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:10 	
108 	<user> <user> 	Fout (3) 	Cannot register tab "PsshippingConfigurationController" because it already exists 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:10 	
107 	<user> <user> 	Fout (3) 	Cannot register tab "PsshippingConfigurationController" because it already exists 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:10 	
106 	<user> <user> 	Fout (3) 	Cannot register tab "PsshippingOrdersController" because it already exists 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:10 	
105 	<user> <user> 	Fout (3) 	Cannot register tab "PsshippingOrdersController" because it already exists 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:10 	
104 	<user> <user> 	Fout (3) 	Cannot register tab "PsshippingOrdersController" because it already exists 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:10 	
103 	<user> <user> 	Fout (3) 	Cannot register tab "PsshippingConfigurationController" because it already exists 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:10 	
102 	<user> <user> 	Fout (3) 	Cannot register tab "PsshippingCarrierController" because it already exists 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:10 	
101 	<user> <user> 	Fout (3) 	Cannot register tab "PsshippingCarrierController" because it already exists 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:10 	
100 	<user> <user> 	Fout (3) 	Cannot register tab "PsshippingCarrierController" because it already exists 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:03:10 	
64 	<user> <user> 	Fout (3) 	SymfonyCacheClearer: Error while clearing cache for admin env prod using PrestaShop\PrestaShop\Adapter\Cache\Clearer\Symfony\ApplicationKernelCacheClearer: Failed opening required '/var/www/vhosts/<domain.tld>/httpdocs/var/cache/prod/admin/ContainerVXCidX4/getConsole_ErrorListenerService.php' (include_path='.:/opt/plesk/php/7.4/share/pear') 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:02:55 	
61 	<user> <user> 	Fout (3) 	ExecKernelCacheClearer: Could not clear cache for admin env prod result: 127 output: array ( 0 => 'sh: php: command not found', ) 		0 	Winkel <shopname> (id : 1) 	Nederlands (Dutch) 	0 	23‑11‑2025 16:02:47 	
7 	N/B 	Fout (3) 	SymfonyCacheClearer: Error while clearing cache for admin env prod using PrestaShop\PrestaShop\Adapter\Cache\Clearer\Symfony\ApplicationKernelCacheClearer: Failed opening required '/var/www/vhosts/<domain.tld>/httpdocs/var/cache/prod/admin/ContainerLUxxvVc/getConsole_ErrorListenerService.php' (include_path='.:/opt/plesk/php/7.4/share/pear') 		0 	--- 	Nederlands (Dutch) 	0 	23‑11‑2025 16:02:17 	
4 	N/B 	Fout (3) 	ExecKernelCacheClearer: Could not clear cache for admin env prod result: 127 output: array ( 0 => 'sh: php: command not found', ) 		0 	--- 	Nederlands (Dutch) 	0 	23‑11‑2025 16:02:09

I have no idea why the code says something about php 7.4 when the hosting account php setting is set to 8.4.14

[El Patron]

8.4 os9 is experimental

highest recommended is 8.3

learn more here

see of this solves if not post back here

 

[Ch3vr0n]

Generating debug optional cookie info, disables "debug mode". Erasing the optional info while on php 8.3.27 did too. So has to be something 8.4 related?

Is there a way to import a database from an 8.0.3 or something PS (customers, shop items, images) into the 9.0.1 install?

Log does still show a few errors though, not entirely sure if its normal.

Quote

ExecKernelCacheClearer: Could not clear cache for admin env dev result: 127 output: array ( 0 => 'sh: php: command not found', )

SymfonyCacheClearer: Error while clearing cache for admin env dev using PrestaShop\PrestaShop\Adapter\Cache\Clearer\Symfony\ApplicationKernelCacheClearer: Warning: is_dir(): open_basedir restriction in effect. File(Doctrine\ORM\Mapping\ClassMetadata) is not within the allowed path(s): (/var/www/vhosts/<domain.tld>/:/tmp/)

ExecKernelCacheClearer: Could not clear cache for admin env dev result: 127 output: array ( 0 => 'sh: php: command not found', )

SymfonyCacheClearer: Error while clearing cache for admin env prod using PrestaShop\PrestaShop\Adapter\Cache\Clearer\Symfony\ApplicationKernelCacheClearer: Failed opening required '/var/www/vhosts/<domain.tld>/httpdocs/var/cache/prod/admin/ContainerVsY542G/getConsole_ErrorListenerService.php' (include_path='.:/opt/plesk/php/7.4/share/pear')

ExecKernelCacheClearer: Could not clear cache for admin env prod result: 127 output: array ( 0 => 'sh: php: command not found', )

 

Edited Sunday at 04:58 PM by Ch3vr0n (see edit history)

[El Patron]

13 minutes ago, Ch3vr0n said:

Generating debug optional cookie info, disables "debug mode". Erasing the optional info while on php 8.3.27 did too. So has to be something 8.4 related?

Is there a way to import a database from an 8.0.3 or something PS (customers, shop items, images) into the 9.0.1 install?

Log does still show a few errors though, not entirely sure if its normal.

 

I have started using migration pro from addons. 1) using  module upgrade process is tricky, it may be working for 9.0.1 but 9.0.0/1 are beta, .02 will have a of important fxes...9.1 will be the stable version and honestly I feel ps should have waited for 9.1 before releasing to general public, welcome to community tested loool.  2)  using migration pro, you create fresh install and it imports known ps data's...not 3rd party you have to do that manually...the end result though is you will have clean domain files, no old module sources for example that may have vulnerabilities...etc

that being said...if you did your upgrade from ps8 onto staging and your ps8 is in production wait for 9.1 or at least for 9.0.2

 

in summary and it's not clear to me exactly, but yes it could be something as simple as 8.4.  go to 8.3 and see if that clears it up.

 

[Ch3vr0n]

I'm just installing this for a friend. They're familiar with using the shop as a manager, but never really installed it from scratch. They took the managing job over from someone else. Me it's the other way around. I'm familiar with installing php applications, creating databases etc like prestashop but never used it. So i don't know what's normal or not in terms of errors.

9.0.1 is currently operational on 8.3.27? i do have a 2nd copy of Prestashop 8.2.3 installed on a subdomain. Both are fresh installs. How do you recommend i tell them to proceed? Enter all data again from scratch on 8.2.3 and skip 9.x for now until it reaches a more mature state? At least that's what i'm personally leaning too. It's the most recent stable version, and less risk of issues when importing stuff. Downside it'll take longer to get the shop back up and running and loses all prior customer info.

If you have info on how i can set up a staging environment which then can synch to the main domain i'm all ears.

[El Patron]

9 minutes ago, Ch3vr0n said:

I'm just installing this for a friend. They're familiar with using the shop as a manager, but never really installed it from scratch. They took the managing job over from someone else. Me it's the other way around. I'm familiar with installing php applications, creating databases etc like prestashop but never used it. So i don't know what's normal or not in terms of errors.

9.0.1 is currently operational on 8.3.27? i do have a 2nd copy of Prestashop 8.2.3 installed on a subdomain. Both are fresh installs. How do you recommend i tell them to proceed? Enter all data again from scratch on 8.2.3 and skip 9.x for now until it reaches a more mature state? At least that's what i'm personally leaning too. It's the most recent stable version, and less risk of issues when importing stuff. Downside it'll take longer to get the shop back up and running and loses all prior customer info.

If you have info on how i can set up a staging environment which then can synch to the main domain i'm all ears.

tell them to go with 8.2.3, wait for 9.1.0 or later version and then only upgrade if there is new must have feature.  that's my best advice...

https://prestaheroes.com/blogs/prestashop-alerts/prestashop-9-what-s-new-why-to-wait-and-how-to-prepare-for-the-upgrade

[Ch3vr0n]

Will do. 8.2.3 it is and waiting for 9.1.x.

Thanks