OMP error 500 adding metadata

Hi all,
I upgraded an OMP instance form to (moving through intermediate steps).
Now I’m experiencing and Error 500 on XHR calls when I add metadata to a publication:

The detail from apache error log is:

[Thu Aug 10 08:41:10.390648 2023] [proxy_fcgi:error] [pid 10627] [client XX.XX.XX.XX:43008] AH01071: Got error 'PHP message: PHP Parse error:  syntax error, unexpected '=>' (T_DOUBLE_ARROW), expecting ')' in /myOmpPath/api/v1/vocabs/ on line 57', referer: https://myOmpUrl/index.php/mypress/workflow/index/148/5