Uploading To S3 Stopped Working, Error 500

I always upload my photos to Amazon S3. It's been working great until I had to move my server and upgraded to the latest version of Sytist (5.25)
Now I get a 500 server error when I try to upload photos to S3.

I am pretty sure it's a problem on the Sytist server, not Amazon S3 since I can see all my previous photos on S3 in Sytist. 

Here's the error log for today when I tried to upload a photo to Sytist --> S3:

[14-Feb-2025 04:52:21 America/Los_Angeles] PHP Fatal error:  Uncaught TypeError: mktime(): Argument #6 ($year) must be of type ?int, string given in /var/www/sy-inc/photos_functions.php:187
Stack trace:
#0 /var/www/sy-inc/photos_functions.php(187): mktime()
#1 /var/www/sy-inc/sy-thumbnails.php(229): getSearchString()
#2 {main}
  thrown in /var/www/sy-inc/photos_functions.php on line 187
[14-Feb-2025 04:53:17 America/Los_Angeles] PHP Fatal error:  Uncaught TypeError: mktime(): Argument #6 ($year) must be of type ?int, string given in /var/www/sy-inc/photos_functions.php:187
Stack trace:
#0 /var/www/sy-inc/photos_functions.php(187): mktime()
#1 /var/www/sy-inc/sy-thumbnails.php(229): getSearchString()
#2 {main}
  thrown in /var/www/sy-inc/photos_functions.php on line 187
[14-Feb-2025 09:40:19 America/Los_Angeles] PHP Fatal error:  Uncaught Error: Call to undefined function JmesPathmb_strlen() in /var/www/df-admin/aws/JmesPath/Lexer.php:343
Stack trace:
#0 /var/www/df-admin/aws/JmesPath/Parser.php(76): JmesPathLexer->tokenize()
#1 /var/www/df-admin/aws/JmesPath/AstRuntime.php(42): JmesPathParser->parse()
#2 /var/www/df-admin/aws/JmesPath/Env.php(33): JmesPathAstRuntime->__invoke()
#3 /var/www/df-admin/aws/Aws/Endpoint/PartitionEndpointProvider.php(117): JmesPathEnv::search()
#4 /var/www/df-admin/aws/Aws/Endpoint/PartitionEndpointProvider.php(99): AwsEndpointPartitionEndpointProvider::mergePrefixData()
#5 /var/www/df-admin/aws/Aws/ClientResolver.php(704): AwsEndpointPartitionEndpointProvider::defaultProvider()
#6 /var/www/df-admin/aws/Aws/ClientResolver.php(286): AwsClientResolver::_default_endpoint_provider()
#7 /var/www/df-admin/aws/Aws/AwsClient.php(187): AwsClientResolver->resolve()
#8 /var/www/df-admin/aws/Aws/S3/S3Client.php(325): AwsAwsClient->__construct()
#9 /var/www/df-admin/S3.V3.php(18): AwsS3S3Client->__construct()
#10 /var/www/df-admin/w-move-amazon.php(26): require('...')
#11 {main}
  thrown in /var/www/df-admin/aws/JmesPath/Lexer.php on line 343
[14-Feb-2025 10:10:53 America/Los_Angeles] PHP Fatal error:  Uncaught Error: Call to undefined function JmesPathmb_strlen() in /var/www/df-admin/aws/JmesPath/Lexer.php:343
Stack trace:
#0 /var/www/df-admin/aws/JmesPath/Parser.php(76): JmesPathLexer->tokenize()
#1 /var/www/df-admin/aws/JmesPath/AstRuntime.php(42): JmesPathParser->parse()
#2 /var/www/df-admin/aws/JmesPath/Env.php(33): JmesPathAstRuntime->__invoke()
#3 /var/www/df-admin/aws/Aws/Endpoint/PartitionEndpointProvider.php(117): JmesPathEnv::search()
#4 /var/www/df-admin/aws/Aws/Endpoint/PartitionEndpointProvider.php(99): AwsEndpointPartitionEndpointProvider::mergePrefixData()
#5 /var/www/df-admin/aws/Aws/ClientResolver.php(704): AwsEndpointPartitionEndpointProvider::defaultProvider()
#6 /var/www/df-admin/aws/Aws/ClientResolver.php(286): AwsClientResolver::_default_endpoint_provider()
#7 /var/www/df-admin/aws/Aws/AwsClient.php(187): AwsClientResolver->resolve()
#8 /var/www/df-admin/aws/Aws/S3/S3Client.php(325): AwsAwsClient->__construct()
#9 /var/www/df-admin/S3.V3.php(18): AwsS3S3Client->__construct()
#10 /var/www/df-admin/upload/sytist-upload-process.php(972): require('...')
#11 {main}
  thrown in /var/www/df-admin/aws/JmesPath/Lexer.php on line 343

Looks like the php mbstring extension is missing on the new server. Contact your host and have them install / enable it.