For a long time, this article helped me, thank you!
The original address: https://www.cnblogs.com/zhenfei/p/4425874.html

This issue involves 64-bit Oracle services and 32-bit clients causing problems.
The environment is as follows: Win8.1 + 64-bit Oracle 11.1 server, client because of the use of 32-bit program, do not support 64-bit Oracle client, so use 32-bit 10.2 InstantClient package.
Problem: Unable to connect oracle server, PLSQL and SQLPLUS all connect normally, Error Error while trying to retrieve Text for Error orA-01019.
The Oracle documentation describes this error as:
Ora-01019: incapable to allocate memory in the user
Cause: the user side memory allocator returns error.
Action: Increase the processes heap size or switch to the old set of calls.
 
Solution:
The reason for this seems to be that ODBC USES drivers provided by systems other than ORACLE_HOME instead of using drivers provided by Oracle. It’s obviously not a memory problem. So the first step is:
1. Add ORACLE_HOME to the environment variable to point to the 64-bit installation directory instead of instantClient. I think this step would allow Windows to use a matching file to drive
After you do the first step, and then connect, the error message becomes an error that you cannot allocate memory. And then the second step
2. Replace 10.2 Instantclinet package with 11.1 matching 32-bit InstantClient package
After changing, the connection is normal.
 
The tns_admin and PATH variables in the environment can both point to the 32-bit instantClient package location path.